Skype announced a version of its Skype Lite VOIP software for Android at CES last week. Skype Lite, currently in beta, is available for several mobile phones that support Java.
Skype Lite for Android will let users make a local call over standard voice channels then convert it to VOIP, allowing international calls to be made at local call rates. The best part is that the technology doesn't require a high-speed data connection to do its magic, “Call on Skype wherever you are - no WiFi or 3G required” goes the marketing refrain.
With the technology available now (video) it's hard to imagine that Skype doesn't have something similar in development for the iPhone and iPod touch.
Porting Skype Lite to iPhone is far from trivial though and although Apple allows VOIP apps (Fring, Truphone) in the App Store, Apple’s partner operators (read AT&T) probably won't be thrilled at the prospect of customers converting international calls into local calls.