I was at Tmo Corp booth at the mall this last weekend, and the guy there told me that the Wifi enabled phones can make calls using internet without Tmo routers or special setting. Is it true? I know Tmo used to give its routers for this purpose. If it is true, how about other carriers (like AT&T or Sprint)? I just wonder how it works. Do those phones has a special software inside? Thank you.
It's true and it's a feature called UMA calling. The phone has to support UMA (software and hardware is involved), not just have WiFi. Several T-Mobile phones have this feature. It does work with most any router-- we test that service with a non-T-Mo router when we review their UMA phones and it works great. I believe T-Mo currently charges $10/month to use this service. Even if you don't use their router or Hotspot, you still have to pay the fee or they won't enable the feature on the phone.
No other US carrier offers this technology.
-------------------- Lisa Gade Editor in Chief, MobileTechReview