This mesh enables a VoIP call, not a normal cellular call, originating on any of the phones to be carried across the mesh until it reaches a phone that is within range of a mobile base station. It then enters the public telephone network as a VoIP call via any available VoIP service for which the Serval client has been configured.
Alternatively the link to the cellular network could be provided by a dedicated Serval device - the Serval software running on a PC.
Dr Paul Gardner-Stephen, who kicked off the Serval project in the wake of the 2010 Haiti earthquake, has just received a $US400,000 fellowship from the philanthropic Shuttleworth Foundation to further develop Serval.
Gardner-Stephen said: "The Serval Project isn't a threat to the telcos. In fact, it will complement the conventional carriers by offloading 'edge-traffic' from the networks which will be burdened by increasing data volumes and video calls. With the generous support of the Shuttleworth Foundation, we'll be able to advance the cause of the Serval Project to address these global communications needs."
According to the University "This funding will enable Dr Gardner-Stephen's team to take the technology from concept-proven capacity to make voice calls, send SMS and map locations and features through to a refined, end-user ready product."
Gardner-Stephens told iTWire that, in the open in rural areas, communication between two phones was possible over up to 1km. However he is eying the possibility of using the guard band at 915MHz between 900MHzfrequencies allocated to cellular to extend this up to perhaps 20kms. This band is class licensed for scientific, instrumentation and medical use at up to 1Watt. The higher power and lower frequency compared to WiFi's 2.4GHz and the option of using different modulation schemes would greatly increase the range, he said.
Although it is available from the Android Market the Serval software is still very much in the development stage, and not yet suitable for use by the general public - the project team hopes to get others participating in the development. It comes with warnings of potential dire consequences, but adds: "It is however fun to use to discover the potential of free and open mesh telephony."
Gardner-Stephen anticipates that a robust version of the Serval Project software will be available free to the public within 12 months. "That will allow friends travelling in convoy in the Outback, for instance, to call each other for free from car to car," he said. "We are actively working with Outback communities to trial the technology to provide remote communities with mobile phone and Internet access."
"We would expect that in five years' time every mobile phone that's manufactured will have our technology," he said.