Two years ago if you asked carriers about mobile VoIP -- the use of voice-over-IP services on cell phones -- they would ignore your question. There was an unwritten rule that mobile VoIP was taboo. Carriers seemed to be afraid that VoIP would disrupt their market they way it had affected the wireline telecom world. At this year's 3GSM, the carriers are finally talking about mobile VoIP, but they seem to be in denial about its potential.T-Mobile International CEO Hamid Akhavan this week at 3GSM said that VoIP will not be as prevalent on mobile devices as it is on the desktop. He warned that there were too many issues with mobility to make mobile VoIP a viable alternative to GSM networks.

Tell that to Fring. Earlier this month Fring launched client that works seamlessly with popular peer-to-peer VoIP services Skype and Google Talk.

Fring has been demoing its service here at 3GSM. I had a chance to take a peek at it here and frankly, I was impressed. I think T-Mobile has more to worry about than they are letting on.

And Fring isn't alone. Another service, Jajah, lets users set up and receive mobile calls from their cell phones, all for free.

I mean, even Microsoft is embracing mobile VoIP with Windows Mobile 6.

Do the carriers really think that if they just stick their heads in the sand, mobile VoIP will go away?