Voice over WiFi (VoWiFi) after years of relative wheel-spin seems to have found traction in the telco and cable communities, especially in the US where cable companies have for many years threatened to deploy it - now they are deploying it and telcos have noticed.

Little wonder that VoWiFi is one of the big, bouncy themes at Mobile World Congress this year.

“You always know when something is hot when every other company tries to position into it,” says Ken Kolderup, who might be fairly described as a VoWiFi pioneer, having been one of the team at VoWiFi specialist Kineto, now CMO at Taqua, the company which bought it last year. “Any  company that has in the past has anything to do with WiFi in any way, shape or form is now all of a sudden in the voice over WiFi space,” he told me.

Certainly there is a lot it about.  At MWC WiFi specialists abound and more than a smattering of enabled operators.  For instance, France Telecom’s Libon is showing a unified communications app for iOS and Android with an extra ‘Reach Me’ feature that allows Android Libon customers to receive and place calls, using their mobile number when on WiFi.

Why, I asked Ken, was there such a sudden acceptance of the technology and the service concept? I had been asking the ‘Wot about voice over WiFi?’ question at the previous four or five MWC’s usually to be met with a vaguely hostile response, now suddenly it’s all changed.

“Timing and circumstance,” he says. “In fact several things have kind of come together over the past 12 months or so

First, we’ve had what Ken calls the “Femtocell diversion” which saw the industry waste half a decade on a  a dead-end and stalled carrier progress on WiFi as a result. “A lot of operators were very enamoured but the economics and technical realities ruled that approach out..  I guess we just had to get through the hype-cycle.

But in the last 24 months carriers have changed things.  First, most users in developed markets have smartphones and most were connecting to WiFi already. Secondly, the network cores are fast going IP with the advent of LTE (just easier to transparently add WiFi to the mix).

Also with high-powered smartphones comes the nascent ability to add VoWiFi as a downloadable app -  although this was probably feasible before, Kineto had always followed telco instructions and embedded the client software. But the final heave came from Cupertino.

“We had operators nearly converted, the phones attached to their networks were now mostly capable of handling VoWiFi and they had a coverage problem indoors - there was their opportunity,” says Ken. “But for one last bit of resistance we would hear, ‘but somewhere between 20 and 40 per cent of my users have iPhones.’"

Then Apple announced that it was supporting WiFi calling on the iPhone (it was already supported in Android). "The floodgates opened for us and now we are engaged with nearly every operator around the world,” he claimed.  “The miracle of Apple is the way it changes the cycle.  If Apple does it then it’s ready for primetime. "