The chance for more of us to make VoIP calls via our mobile phones has grown dramatically over the last 3 years.

According to the Wi-Fi Alliance - the group that certifies the inclusion of the technology in mobile phones - it has certified nearly 100 Wi-Fi phones since 2004, with the promise of more to come this year including Apple's iPhone.

According to the Alliance, the days when the perception was "Wi-Fi versus cellular" are over with major operators, including UK BT, "aggressively" pushing the technology.

The majority of smartphones now come with the technology and a number of releases at this years 3GSM are Wi-Fi enabled.

However some commentators believe that the roll out of cheap Wi-Fi services are holding back any full scale adoption. "Wi-Fi might be free in your home, but out in the real world it's very different", an industry expert told Pocket-lint.