From Skype Blog (http://blogs.skype.com/en/2010/12/unhcr.html)
Skype developed a bespoke, low-bandwidth version of Skype for use in 120 hardship locations served by UNHCR staff members around the world. Aid workers in these locations are typically separated from their families for months at a time, sometimes with very little notice, and have limited opportunities for communication.
I saw few replies to the original post asking for beta release of the low bandwidth version to public. While I don't really need the low bandwidth version , I guess the request is for the developing world and it makes a difference if it can be bundled with mobile phones and uses mobile broadband. This can change the way people communicate in developing world like India where fixed broadband penetration is still 0.8% while mobile penetration is ~ 63%. With most of the operators in India launching/planning to launch 3G services which can give ~500/100 Kbps in downlink/uplink easily can work very well with Skype low bandwidth version.
Anyways the engineer in me tried to understand the interesting point which is how does this low bandwidth works?. To start below is a slidepack showing how Skype works.
A detailed presentation can be found here (disi.unitn.it/locigno/didattica/AdNet/08-09/05_VoIP-Skype_H.pdf)
* The required (basic minimum) bandwidth for skype call is 30Kbps downlink / 30Kbps uplink. This can be achievable with a typical dial-up modem or a good gprs connection.
* Skype protocol does a great job with jitter so this may not be a big problem
The biggest challenge will be to ensure that the skype client in UN closed group doesn't connect to a supernode which is far far away. This can be easily overcome by putting a super node in every nation with some good internet connectivity and availability. Skype always claim that they provide service with bare minimum infrastructure and the network is self sustainable with super nodes automatically selected. For the UN scenario they might have invested in some servers. But whatever it may be end of the day this is for one good purpose so well done skype.
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