About a year ago I wrote a small piece over using VOIP and UMTS, stating that that might be a cheap alternative over calling, but it wouldn’t probably work because of high delay (and jitter).
Apperantly, it does work. And apperantly, other people have been using it: Vodafone has announced (although I can’t find it on the original german page) on friday that using VOIP on their UMTS network will be made technically impossible.
A bit of a dissapointment to me really, instead of grasping new opportunities, Vodafone tries to stop technological improvements by just disallowing them (that won’t work anyway…).