Cherry is a belgian company that has come up with a really interesting service of switching live calls between WiFi and GSM networks. Let me give you an example. Think of your favorite mobile software that you use to make WiFi calls. I use several software like including Skype and Fring. But the limitation is, I cant go out of WiFi coverage. Obviously, I dont have a city wide free WiFi coverage as well, well, no city has that. I do not enjoy the freedom of movement that one enjoys on a normal GSM call.
If I’m using a Cherry’s solution, I can continue talking and can walk out of my home or office. The call can initially connect over WiFi. When the isgnal is weak and you are moving out of the WiFi range, the call switches to a GSM call without dropping the call. The other party never gets to know about the switch. Marvelous!! Is’nt it?
This essentially means that you are switching back and forth between free and more expensive calls. The idea was meant to be implemented and now people will start working on solutions that will let you switch between wifi/gsm/wimax/eVdo and what not. The idea is to simply keep the cost low.