Cellphone calling - over WiFi

Traffic congestion is a serious problem for mobile carriers - too many users, and not enough capacity.  For those of us who live in New York, this is just a way of life - but it need not be this way.  The problem thus far has been one of simple economics, demand has always exceeded supply, and the more capacity that the carriers provide, the more  actuall use people make of the network, thus negating the benefits.
Carriers are - slowly - starting to think laterally about this problem, with WiFi Calling emerging as a leader.

The basics are fairly straightforward - when the cellphone is connected to a WiFi network everything is routed over it.  Not just  YouTube videos and web-access - everything, including the user's calls and SMS.  The experience is (or should be) seamless - as far as the user is concerned there is no difference in what the phone is doing, it is only in how the phone is doing it, and most users could care less about that.

T-MOBILE'S "Free Wi-Fi Calling" - powered by Kineto - is a case in point.  When a phone is in an accessible WiFi zone, it automagically turns on WiFi and turns off the cellular radio, sending everything through the WiFi network.  Its pretty ridiculously easy to use, handling login pages with aplomb, and even supporting rules like Offload only voice to WiFi unless I'm at Panera where I know that I have the bandwidth to deal with my Youtube addiction.
   Historically carriers have been loath to move traffic off their networks - they prefer to keep, or increase ARPU (Average Revenue Per User) through usage limits and bandwidth caps.  AT&T and Sprint have chosen to go down the femtocell path, keeping traffic on their cellular networks (even if it is in a femtocell zone).
    In this case, however, T-Mobile is definitely marching to the beat of a different drum.  They have chosen to go with with UMA (Unlicensed Mobile Access) which is basically part of the international GSM standard.  To simplify this drastically, when the phone is connected via WiFi, it sends all its data over a VPN to the carrier, who deals with it exactly as if it were coming over the cellular network (Much more and gorier information here).
   T-Mobile originally counted your voice/SMS usage against your limits, but has now made it completely free.

REPUBLIC WIRELESS (a division of Bandwidth.com) is doing something similar, albeit with customized handsets.  Republic provides customized handsets - currently the LG Optimus, but with more to follow - that do all of their communications over WiFi.  However, when the phone is outside WiFi range, it automagically switches to Sprint's cellular network.  Unlike T-Mobile, the service isn't completely transparent, with a brief tone being played whenever there is a switch. 
   The disruptive part of their offering is their price-point - $19/month for an all you can eat package which is far, far below what anybody else is offering.  Republic is betting that most people will be in WiFi range, and their ToS does have a use the cellular network too much, and we kick you out feature.  From that perspective, the tone that gets played when switching networks is a feature, serving as an appropriate warning to users... (see Update below)

O2 in Britain is doing something similar, allowing their users to route their calls and SMS over wifi.  Their solution is based on Jajah, which they purchased in 2009, but the user experience is exactly the same, i.e., seamless

In the coming year, I expect to see more in this general vein, i.e., carriers working on providing seamless access to voice services regardless of the network that these services are being provided on.  In short, voice becoming Yet Another App on the net.


 Postscript:

 Yes, I am completely ignoring the App side of the house.  There are any number of applications (Acrobits, Fring, Gogii, Skype) available that provide Internet-based calling (and with Gogii - SMS) services on your cellphone, some of which are also carrier supported (Hello Bobsled!).  However, these are all out-of-band services, i.e., they are not natively integrated into your cell-phone experience, with - usually - separate dialers, bills, and UI experiences. This distinction is becoming somewhat diffuse, with Rebtel's latest iPhone App giving the user to switch the call to and from WiFi during the call.  All this, however, is fodder for a different post...

Update:  In a blog post, Republic announced that usage limits are now history.  The caveat is that this is through the beta period, quote --   

"We won’t end beta until we either achieve economic sustainability or become convinced that doing so is impossible. In the event that we end beta with a decision to abandon or change our unlimited offering, we’ll give you the option of canceling for a full refund for your device at that time."