|Developer(s)||Telegram FZ LLC|
Telegram Messenger Inc.
|Initial release||14 August 2013|
|Platform||Android, iOS, Windows Phone, Windows NT, macOS, GNU/Linux, Web platform|
|Available in||14 languages|
|License||GNU GPLv2 or GPLv3 (clients), proprietary (server)|
|Alexa rank||188 (April 2020[update])|
|Headquarters||London, United Kingdom|
Dubai, United Arab Emirates
Telegram is a cloud-based instant messaging and voice over IP service. Telegram client apps are available for Android, iOS, Windows Phone, Windows, macOS and GNU/Linux. Users can send messages and exchange photos, videos, stickers, audio and files of any type.
Telegram's client-side code is free software, whereas its server-side code is closed-source and proprietary. The service also provides APIs to independent developers. As of April 2020, Telegram had 400 million monthly active users. An announcement at that time included a promise to implement secure group video calls later in 2020.
Telegram was launched in 2013 by the brothers Nikolai and Pavel Durov. Previously, the pair founded the Russian social network VK, which they left when it was taken over by the Mail.ru Group. Nikolai Durov created the MTProto protocol that is the basis for the messenger, while Pavel provided financial support and infrastructure through his Digital Fortress fund with partner Axel Neff joining as a second co-founder. The Company and the App was started in Russia and shifted to Germany. Telegram Messenger LLP states that its end goal is not to bring profit, but it is not currently structured as a non-profit organization.
Telegram is registered as both an English LLP and an American LLC. It does not disclose where it rents offices or which legal entities it uses to rent them, citing the need to "shelter the team from unnecessary influence" and protect users from governmental data requests. Pavel Durov has said that the service was headquartered in Berlin, Germany, between 2014 and early 2015, but moved to different jurisdictions after failing to obtain residence permits for everyone on the team. Durov left Russia and is said to be moving from country to country with a small group of computer programmers consisting of 15 core members. According to press reports, Telegram had employees in St. Petersburg. The Telegram team is currently based in Dubai.
In October 2013, Telegram had 100,000 daily active users. On 24 March 2014, Telegram announced that it had reached 35 million monthly users and 15 million daily active users. In October 2014, South Korean governmental surveillance plans drove many of its citizens to switch to Telegram. In December 2014, Telegram announced that it had 50 million active users, generating 1 billion daily messages, and that it had 1 million new users signing up on its service every week, traffic doubled in five months with 2 billion daily messages. In September 2015, an announcement stated that the app had 60 million active users and delivered 12 billion daily messages.
In February 2016, Telegram announced that it had 100 million monthly active users, with 350,000 new users signing up every day, delivering 15 billion messages daily. In December 2017, Telegram reached 180 million monthly active users. In March 2018, Telegram reached 200 million monthly active users. On 14 March 2019, Pavel Durov claimed that "3 million new users signed up for Telegram within the last 24 hours." Durov did not specify what prompted this flood of new sign-ups, but the period matched a prolonged technical outage experienced by Facebook and its family of apps, including Instagram. On 24 April 2020 Telegram announced it had reached 400 million monthly active users.
According to the U.S. Securities and Exchange Commission, the number of monthly Telegram users as of October 2019 is 300 million people worldwide.
Telegram accounts are tied to telephone numbers and are verified by SMS. Users can add multiple devices to their account and receive messages on each one. Connected devices can be removed individually or all at once. The associated number can be changed at any time and when doing so, the user's contacts will receive the new number automatically. In addition, a user can set up an alias that allows them to send and receive messages without exposing their phone number. Telegram accounts can be deleted at any time and they are deleted automatically after six months of inactivity by default, which can optionally be changed to 1 month and 12 months. Users can replace exact "last seen" timestamps with broader messages such as "last seen recently".
The default method of authentication that Telegram uses for logins is SMS-based single-factor authentication. All that is needed in order to log into an account and gain access to that user's cloud-based messages is a one-time passcode that is sent via SMS to the user's phone number. These login SMS messages are known to have been intercepted in Iran, Russia and Germany, possibly in coordination with phone companies. Pavel Durov has said that Telegram users in "troubled countries" should enable two-factor authentication by creating passwords, which Telegram allows, but does not require.
In June 2015, Telegram launched a platform for third-party developers to create bots. Bots are Telegram accounts operated by programs. They can respond to messages or mentions, can be invited into groups and can be integrated into other programs. It also accepts online payments with credit cards and Apple Pay. Dutch website Tweakers reported that an invited bot can potentially read all group messages when the bot controller changes the access settings silently at a later point in time. Telegram pointed out that it considered implementing a feature that would announce such a status change within the relevant group. Also, there are inline bots, which can be used from any chat screen. In order to activate an inline bot, user needs to type in the message field a bot's username and query. The bot then will offer its content. User can choose from that content and send it within a chat.
In September 2015, Telegram added channels. Channels are a form of one-way messaging where admins are able to post messages but other users are not. Any user is able to create and subscribe to channels. Channels can be created for broadcasting messages to an unlimited number of subscribers. Channels can be publicly available with an alias and a permanent URL so anyone can join. Users who join a channel can see the entire message history. Users can join and leave channels at any time. Depending on a channel's settings, messages may be signed with the channel's name or with the username of the admin who posted them. Non-admin users are unable to see other users who've subscribed to the channel. Furthermore, users can mute a channel, meaning that the user will still receive messages, but won't be notified. Admins can give permission to post comments on the Telegram channel with help of bots. The admin of the channel can obtain general data about the channel. Each message has its own view counter, showing how many users have seen this message, this includes views from forwarded messages. As of May 2019, the creator of a channel can add a discussion group, a separate group where messages in the channel are automatically posted for subscribers to communicate.
In December 2019, Bloomberg moved their messenger-based newsletter service from WhatsApp to Telegram after the former banned bulk and automated messaging. The news service is attempting to grow its audience outside the U.S.
In the latest update of May 2020 Telegram has added custom folders in which one can filter out and put personal chats, groups, channels, contacts, non-contacts, and selected chats/groups/channels in different and customized folders.
Stickers are cloud-based, high-definition images intended to provide more expressive emoji. When typing in an emoji, the user is offered to send the respective sticker instead. Stickers come in collections called "sets", and multiple stickers can be offered for one emoji. Telegram comes with one default sticker set, but users can install additional sticker sets provided by third-party contributors. Sticker sets installed from one client become automatically available to all other clients. Sticker images use WebP file format, which is better optimized to be transmitted over internet.
Drafts are unfinished messages synced across user devices. One can start typing a message on one device and continue on another. The draft will persist in editing area on any device until it is sent or removed.
Messages can also be sent with client-to-client encryption in so-called secret chats. These messages are encrypted with the service's MTProto protocol. Unlike Telegram's cloud-based messages, messages sent within a secret chat can be accessed only on the device upon which the secret chat was initiated and the device upon which the secret chat was accepted; they cannot be accessed on other devices. Messages sent within secret chats can, in principle, be deleted at any time and can optionally self-destruct.
Secret chats have to be initiated and accepted by an invitation, upon which the encryption keys for the session are exchanged. Users in a secret chat can verify that no man-in-the-middle attack has occurred by comparing pictures that visualize their public key fingerprints.
According to Telegram, secret chats have supported perfect forward secrecy since December 2014. Encryption keys are periodically changed after a key has been used more than 100 times or has been in use for more than a week. Old encryption keys are destroyed.
Secret chats are not available for groups or channels.
In the end of March 2017, Telegram introduced its own voice calls. The calls are built upon the end-to-end encryption of Secret Chats. Connection is established as peer-to-peer whenever possible, otherwise the closest server to the client is used. According to Telegram, there is a neural network working to learn various technical parameters about a call to provide better quality of the service for future uses. After a brief initial trial in Western Europe, voice calls are now available for use in most countries.
Telescope (video messages)
Since version 4.1, released in May 2017, Telegram offers a dedicated video hosting platform called Telescope. The round videos can be up to one minute long and autoplay. When posted in a public channel on Telegram, the videos are also uploaded to and viewable without an account. However, Telegram video messages and "Telescope" videos sent within non-public chats or groups are not published.
For either 15 minutes, one hour, or eight hours, Telegram users can share their live location in a chat since version 4.4 released in October 2017. If multiple users share their live location within a group, they are shown on an interactive map. Sharing the 'live location' can be stopped at any time.
In February 2018, Telegram launched their social login feature to its users, named as Telegram Login. It features a website widget that could be embedded into websites, allowing users to sign into a third party website with their Telegram account. The gateway sends users' Telegram name, username, and profile picture to the website owner, while users' phone number remains hidden. The gateway is integrated with a bot, which is linked with the developer's specific website domain.
In July 2018, Telegram introduced their online authorisation and identity management system, Telegram Passport, for platforms that require real-life identification. It asks users to upload their own official documents such as passport, identity card, driver license, etc. When an online service requires such identification documents and verification, it forwards the information to the platform with the user's permission. Telegram stated that it does not have access to the data, while the platform will only share the information to the authorised recipient. However, the service was criticised for being vulnerable to online brute force attacks.
Polls are a feature of Telegram that are currently available on Android, iOS and the desktop applications. Polls have the option to be anonymous or visible. A user can enter multiple options into the poll. Quiz mode can also be enabled where a user can select the right answer for their poll and leave it to the group to guess. Quiz bots can also be added to track correct answers and even provide a global leaderboard.
Native file format support
The official Telegram clients support sending any file format extensions. Natively supported in their viewer/player in mobile and desktops versions of Telegram are the common media formats - JPEG, PNG, WebP for images and H.264 and HEVC in videos in MP4 container and MP3, Vorbis, Opus and AAC for audio.
Send when Online
Telegram adds the scheduled message feature that was launched in a previous update called "Send when Online". This feature will allow users to draft a message and automatically send it when the receiver comes online. The new feature can be found within the Schedule Message option.
The default messages and media use client-server encryption during transit. This data is also encrypted at rest, but can be accessed by Telegram developers, who hold the encryption keys. In addition Telegram provides end-to-end encrypted calls and optional end-to-end encrypted "secret" chats between two online users on smartphone clients. However, the desktop clients (excluding macOS client) do not feature end-to-end encryption, nor is end-to-end encryption available for groups, supergroups, or channels. Telegram has defended the lack of ubiquitous end-to-end encryption by claiming the online-backups that do not use client-side encryption are "the most secure solution currently possible," despite several other chat services such as Signal, Matrix, and WhatsApp offering end-to-end encryption on all platforms.
Telegram uses a symmetric encryption scheme called MTProto. The protocol was developed by Nikolai Durov and other developers at Telegram and is based on 256-bit symmetric AES encryption, 2048-bit RSA encryption and Diffie–Hellman key exchange.
Telegram Messenger LLP has servers in a number of countries throughout the world to improve the response time of their service. Telegram's server-side software is closed-source and proprietary. Pavel Durov has said that it would require a major architectural redesign of the server-side software to connect independent servers to the Telegram cloud.
For users who signed in from the European Economic Area (EEA) or United Kingdom, the General Data Protection Regulations (GDPR) are supported by storing data only on servers in the Netherlands, and designating a London based company as their responsible data controller.
Telegram has various client apps, some developed by Telegram Messenger LLP and some by the community. Most of them are free and open-source and released under the GNU General Public Licence version 2 or 3.
- No cloud backup option for secret chat
|Name||Platform(s)||Official||Source code license||Support for secret chats||Notes|
|Telegram||Android 2.3 or later||Yes||GPLv2 or later||Yes||Supports tablets and Android Wear smart watches. Support synchronisation between multiple devices.|
|Telegram Messenger||iOS 9.0 or later, watchOS 5.0 or later||Yes||GPLv2 or later||Yes||Launched in August 2013 for iPhone and iPod Touch and relaunched in July 2014 with support for iPad and Apple Watch.|
|Telegram X||Android||Yes||Proprietary||Yes||An alternative Telegram client written from scratch, with higher speed, slicker animations, themes and more efficient battery use.
iOS version is written with Swift. Android version based on TDLib. The iOS version was discontinued, with its code merged with the main Telegram app.
|Telegram Messenger||Windows Phone||Yes||GPLv2 or later||Yes||Provide synchronization between all platforms|
|Telegram||Firefox OS||Yes||GPLv3||No||Based on Webogram.|
|Telegram Desktop||Windows, macOS, and GNU/Linux||Yes||GPLv3 with OpenSSL exception||No||Qt-based desktop client. The Windows client is a traditional desktop app published in three flavors:
With installer, portable, Windows Store app.
|Telegram||macOS||Yes||GPLv2||Yes||Native macOS client.|
|Telegram||Google Chrome and Chrome OS||Yes||GPLv3||No||Based on Webogram, published on the Chrome Web Store.|
Telegram has public APIs with which developers can access the same functionality as Telegram's official apps to build their own messaging applications. In February 2015, creators of the unofficial Whatsapp+ client released the Telegram Plus app, later renamed to Plus Messenger, after their original project got a cease-and-desist order from WhatsApp. In September 2015, Samsung released a messaging application based on these APIs.
Telegram also offers an API that allows developers to create bots, which are accounts controlled by programs. In February 2016, Forbes launched an AI-powered news bot that pushes popular stories to subscribers and replies to search queries with relevant articles. TechCrunch launched a similar bot in March 2016.
Telegram's security model has received notable criticism by cryptography experts. They criticized the general security model of permanently storing all contacts, messages and media together with their decryption keys on its servers by default and by not enabling end-to-end encryption for messages by default. Pavel Durov has argued that this is because it helps to avoid third-party unsecure backups, and to allow users to access messages and files from any device. Cryptography experts have furthermore criticized Telegram's use of a custom-designed encryption protocol that has not been proven reliable and secure.
Cryptography experts have expressed both doubts and criticisms on Telegram's MTProto encryption scheme, saying that deploying home-brewed and unproven cryptography may render the encryption vulnerable to bugs that potentially undermine its security, due to a lack of scrutiny. It has also been suggested that Telegram did not employ developers with sufficient expertise or credibility in this field.
Critics have also disputed claims by Telegram that it is "more secure than mass market messengers like WhatsApp and Line", because WhatsApp applies end-to-end encryption to all of its traffic by default and uses the Signal Protocol, which has been "reviewed and endorsed by leading security experts", while Telegram does neither and insecurely stores all messages, media and contacts in their cloud. Since July 2016, Line has also applied end-to-end encryption to all of its messages by default.
The Electronic Frontier Foundation (EFF) listed Telegram on its "Secure Messaging Scorecard" in February 2015. Telegram's default chat function received a score of 4 out of 7 points on the scorecard. It received points for having communications encrypted in transit, having its code open to independent review, having the security design properly documented, and having completed a recent independent security audit. Telegram's default chat function missed points because the communications were not encrypted with keys the provider didn't have access to, users could not verify contacts' identities, and past messages were not secure if the encryption keys were stolen. Telegram's optional secret chat function, which provides end-to-end encryption, received a score of 7 out of 7 points on the scorecard. The EFF said that the results "should not be read as endorsements of individual tools or guarantees of their security", and that they were merely indications that the projects were "on the right track".
In December 2015, two researchers from Aarhus University published a report in which they demonstrated that MTProto does not achieve indistinguishability under chosen-ciphertext attack (IND-CCA) or authenticated encryption. The researchers stressed that the attack was of a theoretical nature and they "did not see any way of turning the attack into a full plaintext-recovery attack". Nevertheless, they said they saw "no reason why [Telegram] should use a less secure encryption scheme when more secure (and at least as efficient) solutions exist". The Telegram team responded that the flaw does not affect message security and that "a future patch would address the concern". Telegram 4.6, released in December 2017, supports MTProto 2.0, which now satisfied the conditions for IND-CCA. MTProto 2.0 is seen by qualified cryptographers as a vast improvement to Telegram's security.
In April 2016, accounts of several Russian opposition members were hijacked by intercepting the SMS messages used for login authorization. In response, Telegram recommended using the optional two-factor authentication feature. In May 2016, the Committee to Protect Journalists and Nate Cardozo, senior staff attorney at Electronic Frontier Foundation, recommended against using Telegram because of "its lack of end-to-end encryption [by default] and its use of non-standard MTProto encryption protocol, which has been publicly criticized by cryptography researchers, including Matthew Green".
In June 2017, Pavel Durov in an interview publicly claimed that U.S. intelligence agencies tried to bribe the company's developers to weaken Telegram's encryption or install a backdoor during their visit to the U.S. in 2016.
In 2018 Telegram sent a message to all Iranian users stating Telegram Talai and Hotgram unofficial clones are not secure.
Telegram promised since at least March 2014 that "all code will be released eventually", including all the various client applications (Android, iOS, desktop, etc.) and the server-side code. As of February 2020, Telegram still hasn't published their server-side source code.
On 9 June 2019, The Intercept released leaked Telegram messages exchanged between current Brazilian Minister of Justice and former judge Sérgio Moro and federal prosecutors. The hypothesis is that either mobile devices were hacked by SIM swap or computers invaded. The Telegram team tweeted that it was either because the user had malware or they were not using 2-step verification.
On 12 June 2019, Telegram confirmed that it suffered a Denial-of-service attack which disrupted normal app functionality for approximately one hour. Pavel Durov tweeted that the IP addresses used in the attack mostly came from China.
In December 2019 media wrote about a numerous Telegram account takeovers of Russian businessmen that involved bypass of SMS second factor authentication. Takeover of Telegram account was also offered on dark web forums for $4000. Group-IB security company suggested SS7 mobile signalling protocol weaknesses, illegal usage of surveillance equipment or telecom insider attacks.
Telegram has organized two cryptography contests to challenge its own security. Third parties were asked to break the service's cryptography and disclose the information contained within a secret chat between two computer-controlled users. A reward of respectively US$200,000 and US$300,000 was offered. Both of these contests expired with no winners. Security researcher Moxie Marlinspike and commenters on Hacker News criticized the first contest for being rigged or framed in Telegram's favor and said that Telegram's statements on the value of these contests as proof of the cryptography's quality are misleading. This was because the cryptography contest could not be won even with completely broken algorithms such as MD2 (hash function) used as key stream extractor, and primives such as the Dual_EC_DRBG that is known to be backdoored.
Countries blocking Telegram:
Telegram was open and working in Iran without any VPN or other circumvention methods in May 2015. In August 2015, the Iranian Ministry of ICT asserted that Telegram had agreed to restrict some of its bots and sticker packs in Iran at the request of the Iranian government. According to an article published on Global Voices, these features were being used by Iranians to "share satirical comments about the Iranian government". The article also noted that "some users are concerned that Telegram's willingness to comply with Iranian government requests might mean future complicity with other Iranian government censorship, or even allow government access to Telegram's data on Iranian users". Telegram has stated that all Telegram chats are private territory and that they do not process any requests related to them. Only requests regarding public content (bots and sticker packs) will be processed. In May 2016, the Iranian government asked all messaging apps, including Telegram, to move all Iranian users' data to Iranian servers. On 20 April 2017, the Iranian government completely blocked Telegram's new voice calls, a service that allows individuals to make calls via secure, end-to-end encryption, and keep their conversations private.
On 30 December 2017, during anti-government demonstrations across Iran, Telegram has shut down a channel of the Iranian opposition that published calls to use Molotov cocktails against the police, after receiving a complaint from the Iranian government. Pavel Durov explained that the reason for the blocking was a "no calls to violence" policy and confirmed that criticizing local authorities, challenging the status quo and engaging in political debate were seen as "OK" by the platform, while "promoting violence" was not. The opposition group promised to comply with Telegram rules and created a new channel which amassed 700,000 subscribers in less than 24 hours. On December, 31, the Iranian government announced that Telegram has been "temporarily restricted" in order to "ensure calm and security" after the company said it refused to shut down peaceful protesting channels. On January, 13, the app was unblocked by an order of the president Hassan Rouhani, who said that "more than 100,000 jobs had been lost” in Iran as a result of the ban on Telegram. Channels of the opposition remain operational.
In March 2018, Iran's chairman for the Committee for Foreign policy and National Security Alaeddin Boroujerdi announced that Telegram has been targeted to be fully blocked in Iran by 20 April 2018, citing Telegram's role in facilitating the winter protests and the need to promote local apps. President Rouhani agreed with the need to break Telegram's monopoly in Iran, but maintained that he was opposed to a new blockade and did not see it as an effective measure to promote local apps. Iranian MP Mahmoud Sadeghi noted that during the two weeks that Telegram was blocked in January 2018, 30 million Iranians (75% of Telegram's users in Iran) did not start using local messaging apps, but instead turned to VPN services to circumvent the block, rendering the blockade ineffective.
Since the end of the riots, the Iranian government employs a customized version of Telegram that is under their domain.
On 27 September 2019, Bijan Ghasemzadeh, the Iranian prosecutor who ordered the block on Telegram, was arrested for charges of corruption. It is unclear whether or not the charges were related to the ban on Telegram.
In July 2015, it was reported that China blocked access to Telegram Messenger. According to state-owned People's Daily, Chinese human rights lawyers used Telegram to criticize the Chinese Government and the Communist Party of China.
On 28 August 2019 the Hong Kong Internet Service Providers Association announced that the Hong Kong government had plans to block Telegram.
In June 2016, it was found that some ISPs in Bahrain had started to block Telegram. In June 2017 the service faced serious pressure from Russian regulator Roscomnadzor, who tried to force Telegram to register in the official telecommunication services registry, which implies serious liability for a registered party. After week-long negotiations and seeming imminent blockage of the service, the conflict ceased after high officials pulled some strings with the regulator.[clarification needed]
On 14 July 2017, eleven domain name servers related to Telegram were banned by the Indonesian Communication and Information Ministry with the possibility of closing all Telegram applications in Indonesia if Telegram did not make a standard operating procedure to maintain content that was considered unlawful in the apps. In August 2017, Indonesian Government has opened full access of Telegram, after Telegram has made self censorship about negative contents mainly radicalism and terrorism. Telegram said that about 10 channels/groups have been deleted from Telegram everyday due to are categorized as negative contents.
In October 2017, Telegram was inaccessible to users in Pakistan, and as of 17 November 2017, it has been completely blocked as per instructions from PTA, Pakistan's largest ISP, PTCL mentioned this in a tweet to a user.
On 13 April 2018, Telegram was banned in Russia by a Moscow court, due to its refusal to grant the Federal Security Service (FSB) access to encryption keys needed to view user communications as required by federal anti-terrorism law. The ban has been enforced by blocking over 19 million IP addresses associated with the service. They include many used by Amazon Web Services and Google Cloud Platform, due to Telegram's use of the providers to route messages. However, this led to unintended collateral damage due to usage of the platforms by other services in the country, including retail, Mastercard SecureCode, and Mail.ru's Tamtam messaging service. Users ended up needing to use VPN to access the service as a result of the internet censorship. On 17 April 2018, Russia asked App Store, Play Store and APKMirror to pull Telegram from stores. App Store and Play Store refused the request of Russian government.
On 28 March 2018, Roskomnadzor reportedly sent a legally binding letter to Apple asking it to remove the app from its Russian App Store and block it from sending push notifications to local users who have already downloaded the app.
On 18 June 2020, Russian government lifted Telegram blocking after it 'agrees to help with extremism investigations'.
In 2019, it was reported that some ISPs in India were blocking Telegram traffic, including its official website. Internet Freedom Foundation, an Indian digital liberties organisation filed an RTI on whether Department of Telecommunications(DoT) had banned Telegram or requested ISPs to block traffic. The response from DoT said that it had no information on why the ISPs were blocking Telegram.
Use by terrorists
In September 2015, in response to a question about the use of Telegram by Islamic State of Iraq and the Levant (ISIS), Pavel Durov stated: "I think that privacy, ultimately, and our right for privacy is more important than our fear of bad things happening, like terrorism." Durov sarcastically suggested to ban words because terrorists use them for communication. ISIS recommended Telegram to its supporters and members and in October 2015 they were able to double the number of followers of their official channel to 9,000. In November 2015, Telegram announced that it had blocked 78 public channels operated by ISIS for spreading propaganda and mass communication. Telegram stated that it would block public channels and bots that are related to terrorism, but it would not honor "politically-motivated censorship" based on "local restrictions on freedom of speech" and that it allowed "peaceful expression of alternative opinions." Telegram's usage for ISIS propaganda reignited the encryption debate and encrypted messaging applications faced new scrutiny. It also led to the Daily Mirror describing Telegram as a "jihadi messaging app".
In August 2016, French anti-terrorism investigators asserted that the two ISIS-directed terrorists who fatally cut the throat of a priest in Saint-Étienne-du-Rouvray in Normandy, France, and videoed the murder, had communicated via Telegram and "used the app to coordinate their plans for the attack". ISIS's media wing subsequently posted a video on Telegram, showing the pair pledging allegiance. A CNN news report stated that Telegram had "become known as a preferred means of communication for the terror group ISIS and was used by the ISIS cell that plotted the Paris terror attacks in November" after the attacks..
In July 2017, Director General of Application and Informatics of the Indonesian Ministry of Communication and Informatics, Semuel Abrijani Pangerapan, said eleven Telegram DNS servers were blocked because many channels in the service "promoted radicalism, terrorism, hatred, bomb assembly, civil attack, disturbing images, and other propaganda contrary to Indonesian laws and regulations." In August 2017, Indonesia lifted the block after countermeasures against negative content were deployed in association with Telegram LLP.
In November 2019, Telegram participated in Europol's Internet Referral Action Day. As a result, Telegram expanded and strengthened its terrorist content detection and removal efforts. Over 43,000 terrorist-related bots and channels were removed from Telegram. According to U.S. officials, the crackdown on Telegram was especially effective and seems to be having lasting impact. According to Europol, Telegram has put forth considerable effort in removing abusers of its platform.
An article published by Mother Jones magazine on 19 January 2020, says that the Anti-Defamation League has called Telegram a white supremacist "safe haven" and a valuable tool for right-wing extremists. The article said Neo-nazi and fascist hate groups were using the Telegram app to organize a gun rally in Richmond, Virginia, on 20 January 2020. The neo-Nazi white separatist paramilitary hate group The Base switched over to Telegram after being blocked on most social media platforms, including Twitter, YouTube, and Gab, a favorite among extremists. After a number of arrests of The Base members in January 2020, a note appeared on its official Telegram account warning people to stop posting. In August 2019 white supremacist Christopher Cantwell posted anti-Semitic comments on Telegram.
The Anti-Defamation League notes that Telegram was founded by the same two Russian brothers who founded VKontakte (VK), which is known for its lack of moderation when it comes to white supremacism. While Telegram's terms of service prohibit the promotion of violence, they have allowed violent videos posted by mass shooters Brenton Tarrant (Christchurch, New Zealand) and Stephan Balliet (Halle, Germany), although other social media platforms had removed them. The League also points to the RapeWaffen Division channel, which openly advocates rape and murder as part of a race war.
Telegram allows users to report abusive public domain posts and deletes terrorist groups' public chats and child pornography. However, Telegram does not share or redress any abusing report. Telegram (like other messaging apps such as Whatsapp) is still being actively used for illegal purposes, such as cryptocurrency pump-and-dump activities.
2019 Puerto Rico "Telegramgate"
Telegram was the main subject surrounding the 2019 Puerto Rico riots that ended up in the resignation of then Governor Ricardo Rosselló after a Telegram chat leaked with of hundreds of pages of a group chat on the messaging application Telegram between Rosselló and members of his staff from his term. The messages were considered vulgar, racist, and homophobic toward several individuals and groups, and discussed how they would use the media to target potential political opponents.
Telegram prevents users from Iran to mass send or receive porn.
Telegram Open Network ICO
In December 2017, cryptocurrency blog Cointelegraph reported that Telegram was planning to launch a blockchain platform and native cryptocurrency. In January 2018, TechCrunch confirmed the news, referring to multiple sources.
The company put together an Initial Coin Offering (ICO) to fund development of a new blockchain platform, to be called the "Telegram Open Network" (TON). The offering was organised as a SAFT (Simple Agreement for Future Tokens), selling futures on tokens to be called GRAM. A 23-page white paper and a detailed 132-page technical paper for the plan were released.
The offering ran in two rounds, each taking in $850 million. Russian tech news site calculated the first round as offering 2.25 billion tokens at $0.38 each, with a minimum purchase of $20 million, and the second as offering 640 million tokens at $1.33 each, with a minimum purchase of $1 million.
As of April 2018, the firm had reported raising $1.7 billion through the ongoing ICO. Company officials have not made any public statements regarding the ICO. As of spring 2018, the only official sources of information were the two Forms D that Telegram filed with the U.S. Securities and Exchange Commission.
Only the pre-ICO rounds were conducted; the public ICO was cancelled. The network has yet to be released.
On 11 October 2019, the U.S. Securities and Exchange Commission filed an emergency action and obtained a temporary restraining order against Telegram over an alleged unregistered and ongoing digital token offering in the U.S.
On 12 May 2020, Pavel Durov announced the end of Telegram’s active involvement with TON. "Sadly, the US judge is right about one thing: we, the people outside the US, can vote for our presidents and elect our parliaments, but we are still dependent on the United States when it comes to finance and technology (luckily not coffee). The US can use its control over the dollar and the global financial system to shut down any bank or bank account in the world. It can use its control over Apple and Google to remove apps from the App Store and Google Play. So yes, it is true that other countries do not have full sovereignty over what to allow on their territory. Unfortunately, we – the 96% of the world’s population living elsewhere – are dependent on decision makers elected by the 4% living in the US" - said Pavel Durov.
On 30 March 2020, an Elasticsearch database holding 42 million records containing user IDs and phone numbers were exposed online without a password. The accounts listed in the database were those belonging to users in Iran, extracted from an unofficial government sanctioned version of Telegram. It took 11 days for the database to be taken down, but the researchers say the data was accessed by other parties, including a hacker who reported the information to a specialized forum.
On 23 June 2020, 40 million Telegram accounts allegedly surfaced on Dark web according to information security expert corporation UnderTheBreach, tweeting that the leak "Appears to be some sort of a large scale scraping campaign similar to the Iranian scraping campaign we've seen a while back. No idea what data this is from but Telegram should really look into their scraping restrictions" 
Illegal Telegram bot
The chairman of the public organization "Electronic Democracy" Volodymyr Flents on May 11 2020 announced that a Telegram bot appeared on the Web, which sold personal data of citizens of Ukraine. It is estimated that the bot contains data from 26 million Ukrainians registered in the Dіia application. However, subsequently, Deputy Prime Minister and Minister of Digital Transformation Mikhail Fedorov denied fakes about the sale of data from "Dіia". The criminal activity of 25 people has already been confirmed and copies of 30 databases were seized.
Litigation with the SEC and abandonment of the project launch
After a lengthy legal battle between Telegram and the SEC, Judge P. Kevin Castel of the U.S. District Court for the Southern District of New York concluded that Telegram tokens (called “Grams”) would be considered securities if issued. Following that decision, the Telegram Open Network (TON) team announced that they would be unable to launch the project by the expected 30 April 2020 deadline, and as a result, US investors were originally offered two options to receive their money back. Either they could receive 72% of their funds in 2020 in accordance with their signed contracts, or if they opted to wait until April 2021, their investments would be converted into loans to Telegram and repaid at a rate of 110% of their original investments. However, shortly after that announcement Telegram retracted the 110% refund option, having sent follow-up letters to US investors stating that the company would only make good on the 72% repayment option.
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