If you get the chance to own a smartphone capable of WiFi like

You can make free calls with any SIP software that you download from the net. Some of them already have native SIP software e.g. on Windows Mobile 5 or 6

Some interesting SIP compatible software is Fring. Only problem with Fring is inbound calls and dome delays.

Watch out that all of those smartphones will not offer the compatibility with SIP softs.

Extract for Cellular news:

“The fastest growing segment in the market by far is the dual-mode WiFi/cellular VoIP phone, with worldwide units shipping at a phenomenal rate: Infonetics forecasts a 5-year compound annual growth rate of 198% between 2006 and 2010.”

What is dual mode? We can say Smartphone with WiFi and compatible SIP capability. But we have to write about the real first dual mode GSM/VoIP : Pirelli.

Pirelli is not only a great annual calendar or tires, this Italian firm has created one of the first VoIP phone where you could put a SIM card and use it with mobile operator.

Anyhow, how to make free calls on a wifi…to be followed