Ever since Wi-Fi access points started popping up, many have been saying it would be great if there were cellphones that operate over Wi-Fi for free if within range, and otherwise on the regular cell-phone networks. Now, I do at least 50% of my cellphone calls within Wi-Fi coverage, so this could clearly bring down my phone bills if I would have a phone that supported it. NTT DoCoMo just released the NEC N900iL in Japan. Phones like these will definitely impact the voice revenues of operators. Sooner than they realize.
"The phone can operate in three different modes: cell phone only, Wi-Fi phone/PDA only or dual. The handset is designed to stay in dual mode whenever possible, with all calls delivered in the Wi-Fi mode, but the call will be switched to the FOMA network if a caller walks out of the building."