Talking super-wideband with Skype

Jonathan Christensen of Skype announced in March 2009 at eComm the royalty free licensing of its super-wideband codec, SILK. To this end, all Skype calls to +883 iNum numbers are now available in high definition.

Skype’s user base of 480 million users brings HD calling to all of inum’s partner networks. From retail users to enterprises, call centers to call conferencing services and not forgetting the plethora of innovative voice applications available through Voxeo: using iNum they can all be reachable from Skype’s new HD platform.

High definition is made possible because such calls do not travel over the PSTN, ensuring end-to-end wideband capability. The PSTN supports 8,000 audio samples per second, whereas the new SILK codec supports between 16,000 and 24,000 samples per second. This greater sampling rate enables the caller to hear more detail in the conversation: regional dialects and subtle consonantal sounds are represented more clearly on a HD call.

Background noise however is also more easily picked up, and this is why HD requires a better quality microphone and speaker set than traditional PSTN telephony. For HD to work, all components on the voice path need to support high definition.

Call iNum from your cell phone

iNums are so easy to use from IM clients and partner networks, that it seems a shame not to have the same ease of use in countries where the local carriers are yet to open access. It’s easy to store and call inums in your cell phone’s contact list using the pause key when dialling a number. This makes calling iNums on the road just as easy as it is from your laptop or desktop.

On a Nokia phone, hold down the ‘*’-star key for 1 second, and a ‘p’ will appear. On the iPhone, press the ‘*’ key and then the ‘pause’ button at the bottom of the screen. The list of access numbers is available on the website:

For example, to dial the iNum +883 510 000 000 091 for a cell phone which is normally used in California, you would store the following contact on your phone:


Since your cellular plan includes free minutes, and this is a normal local, geographic telephone number, the call to the inum will be included in your standard contract. Soon though, you’ll be able to dial the inum without even this access number!