Mobile broadband modem
A mobile broadband modem, also known as a connect card or data card, is a type of modem that allows a laptop, a personal computer or a router to receive Internet access via a mobile broadband connection instead of using telephone or cable television lines. A mobile Internet user can connect using a wireless modem to a wireless Internet Service Provider (ISP) to get Internet access.
1G and 2G
While some analogue mobile phones provided a standard RJ11 telephone socket into which a normal landline modem could be plugged, this only provided slow dial-up connections, usually 2.4 kilobit per second (kbit/s) or less. The next generation of phones, known as 2G (for 'second generation'), were digital, and offered faster dial-up speeds of 9.6kbit/s or 14.4kbit/s without the need for a separate modem. A further evolution called HSCSD used multiple GSM channels (two or three in each direction) to support up to 43.2kbit/s. All of these technologies still required their users to have a dial-up ISP to connect to and provide the Internet access - it was not provided by the mobile phone network itself.
The release of 2.5G phones with support for packet data changed this. The 2.5G networks break both digital voice and data into small chunks, and mix both onto the network simultaneously in a process called packet switching. This allows the phone to have a voice connection and a data connection at the same time, rather than a single channel that has to be used for one or the other. The network can link the data connection into a company network, but for most users the connection is to the Internet. This allows web browsing on the phone, but a PC can also tap into this service if it connects to the phone. The PC needs to send a special telephone number to the phone to get access to the packet data connection. From the PC's viewpoint, the connection still looks like a normal PPP dial-up link, but it is all terminating on the phone, which then handles the exchange of data with the network. Speeds on 2.5G networks are usually in the 30–50kbit/s range.
3G networks have taken this approach to a higher level, using different underlying technology but the same principles. They routinely provide speeds over 300kbit/s. Due to the now increased internet speed, internet connection sharing via WLAN has become a workable reality. Devices which allow internet connection sharing or other types of routing on cellular networks are called also cellular routers.
A further evolution is the 3.5G technology HSDPA, which provides speeds of multiple Megabits per second. Several of the mobile network operators that provide 3G or faster wireless internet access offer plans and wireless modems that enable computers to connect to and access the internet. These wireless modems are typically in the form of a small USB based device or a small, portable mobile hotspot that acts as a WiFi access point (hotspot) to enable multiple devices to connect to the internet. WiMAX based services that provide high speed wireless internet access are available in some countries and also rely on wireless modems that connect to the provider's wireless network. Wireless USB Modems are nicknamed as "Dongles".
Early 3G mobile broadband modems used the PCMCIA or ExpressCard ports, commonly found on legacy laptops. The expression "connect card" (instead of connection card) had been registered and used the first time by Vodafone as brand for its products but now is become a brandnomer or genericized trademark used in colloquial or commercial speech for similar product, made by different manufacturers, too. Major producers are Huawei, Option N.V., Novatel Wireless. More recently, the expression "connect card" is also used to identify internet USB keys. Vodafone brands this type of device as a Vodem.
Often a mobile network operator will supply a 'locked' modem or other wireless device that can only be used on their network. It is possible to use online unlocking services that will remove the 'lock' so the device accepts SIM cards from any network.
Standalone mobile broadband modems are designed to be connected directly to one computer. In the past, these used the PCMCIA, ExpressCard and Compact Flash standards to connect to the computer. These standards have become deprecated by the end of the 2000s in favour of USB-based modems, which are compatible with a greater number of devices. Some models have a built-in GPS chip, while others do not.
Many mobile broadband modems sold nowadays also have built-in routing capabilities. They provide traditional networking interfaces such as Ethernet, USB and Wi-Fi. Models are available for both consumers and enterprises. Some require the use of an AC adapter, while others are portable and can also be powered by a USB connection or a built-in battery. An RJ11 registered jack is also present on a few of these modems, allowing the connection of a traditional home phone to make cellular calls.
Smartphones and Tethering
Numerous smartphones support the Hayes command set and therefore can be used as a mobile broadband modem, although several mobile network operators charge a fee for this feature. Other networks have an allowance for full speed mobile broadband access, which—if exceeded—can result in overage charges or slower speeds.
An internet-accessing smartphone may have the same capabilities as a standalone modem, and—when connected directly to a computer—can serve as a standalone modem for the computer. Those smartphones with built-in Wi-Fi also typically include routing and wireless access point features. This method of connecting is commonly referred to as "tethering." 
An example of tethering is, for instance, a desktop computer connecting to the internet through a USB cable connection ("tether") that connects it ("tethers" it) to a smartphone which has (and provides to the computer) internet access. 
When computers are tetherered to a smartphone for internet access, some cellular service providers charge additional cellular broadband access fees or rates to the smartphone consumer. 
Device driver switching
Mobile broadband modems often use a virtual CD-ROM switching utility and have the device drivers on board. Those modems have two modes, a USB flash drive mode and in the other mode they are a modem.Via the USB Protocol.
|Wikimedia Commons has media related to Wireless modems.|
- "airtel 3G Wi-Fi Dongle - 3G Dongle Plans for High Speed Internet".
- "Devices for Portable Wi-Fi & Mobile Hotspot - AT&T".
- "Phone". Sony Xperia (Global UK English).
- Danny Briere; Pat Hurley; Edward Ferris (2008). Wireless Home Networking for Dummies (3 ed.). For Dummies. p. 265. ISBN 978-0-470-25889-7.
- Brian Nadel (November 4, 2011). "Wi-Fi tethering 101: Use a smartphone as a mobile hotspot". Computerworld. Retrieved 2012-01-16.
- Kim, Eugene and Alex Colon, "The Best Mobile Hotspots of 2015", June 10, 2015, PC Magazine retrieved Nov. 4, 2015