Truphone brings free mobile calls over VoIP

London (England) - With computer VoIP services like Skype and Vonage continuing to build consumer base, Truphone is a new London-based start-up going a slightly different route - bringing the same technology to cell phones to enable free or inexpensive calls on the go.

The technology behind Truphone, which is currently only available for select Nokia handsets, is based on the idea that that calls are routed through the Internet instead the more costly networks of mobile carriers. It can be used anywhere where a strong Wi-Fi signal is present, Truphone writes.

According to the technical details on Truphone’s site, calls made via the Truphone service "are routed via Wi-Fi using Session Initiation Protocol (SIP) and Real-time Transport Protocol (RTP). The RTP proxy deals with the Network Address Translation (NAT) used by firewalls, and with transcoding from the Adaptive Multi-Rate (AMR) codec used in the phone to G.711 if required."

In the US and Canada, calls between two Truphone users, or between a Truphone user and someone using another SIP-based VoIP service, are free. And, reportedly until March 31, 2007, calls to any traditional mobile or landline number are free via Truphone as well.

Calls to other countries can be made for a few cents per minute. From the US to a UK or China landline phone, Truphone users get a rate of 3.2 cents/minute. Calls to Mexico City are 3.6 cents/min, and a minute to Japan rings in a 5.5 cents. Other countries around the world range from 2 cents to $1.30 per minute. Calls to cell phones in these countries ups the rate significantly (e.g. 23.1 cents/minute to the UK and 24 cents/minute to Japan). There is no monthly fee to access the Truphone service.

Currently, Truphone is compatible with Nokia E60, E61, and E70. Additionally, the Truphone platform is available for the Series 60 high-end Nokia phones, which includes the N-Gage, the 7610, and most of the N-series models.