iNum Initiative

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The iNum Initiative is a project started in November 2008 by Voxbone to create a global dial code for IP communications. Voxbone is a Belgian company specializing in wholesale telephone numbers for VoIP applications. The International Telecommunication Union allocated a portion of the non-geographic "country code" +883 to this initiative.[1] Specifically, iNums are 15-digit telephone numbers in the +883 5100 area code.

Participating organizations in iNum Initiative[edit]

The iNum Initiative provides free number ranges to IP communications service providers, enterprises, NGOs and Universities. There are approximately 400 organizations that have been allocated iNum number ranges.

Country code +888 has been allocated for OCHA (United Nations Office for the Coordination of Humanitarian Affairs) international disaster response and implemented using the iNum platform.[2]

Networking standards[edit]

The iNum networking is based on SIP standards[3] and supports voice, video and SMS. Transcoding is available between G.711 and G.729. Video codecs supported are H.263+ and H.264. But theoretically any codec, including Skype's SILK and G.722, for Hi-definition voice, will be supported, as long as the origination and terminating network both support it and transcoding is not required.

Access carrier support for new international dial code[edit]

While +883 is a valid ITU dial code and the iNum numbers formally assigned by the ITU, not all access, fixed and mobile carriers know how to route the calls correctly. Skype, Belgacom, British Telecom, Colt, KPN, Sprint USA, Orange Switzerland and Verizon Europe are among the major communications companies that route voice calls to iNum. SMS to iNum is supported by several agreements with major international messaging providers.

The iNum Initiative offers free SIP termination to all service providers who offer it to their customers at or below the cost of a local call, however, it cannot control what the access carrier charges its end users on a retail level. There have been cases of mis-pricing or overcharging by access carriers. End users should inform their providers in these cases that free SIP termination is available to them.

Voxbone also provides a global access number network to reach +883 5100 numbers, so callers can make local calls to iNum when their local carrier does not yet support routing to the code.[4]

Calling iNums by ENUM methods[edit]

iNums can be called by ENUM methods. The Voxbone iNum range (+883 5100) is delegated within the RIPE ENUM registry.[5] Successful ENUM requests to will result in information that can be used to route the call for free.

Calling iNums by SIP URI[edit]

It is possible to call an iNum as a SIP address in the format or

iNum ambassadors[edit]

iNum ambassadors are end users who want to encourage the use of iNums and volunteer their help by contacting their local service providers to encourage their support for voice calls and SMS to iNum at a reasonable retail price.

Redirecting of the iNum Initiative Website[edit]

During the summer 2019, the iNum Initiative Website was redirected over to Voxbone's Website.

See also[edit]


  1. ^ International Telecommunications Union. "International Numbering Resources".
  2. ^ Working Group on Emergency Telecommuncations.
  3. ^ "IETF". RFC 3261.
  4. ^
  5. ^ "RIPE ENUM Working Group Progress Matrix". RIPE ENUM Working Group.

External links[edit]