[davidtheprof]

what really sets Piranha apart, in my view, is the VOIP integration - with Truphone, I wangled a free incoming US number out of them, but it's a different app and number.
with Piranha, it's the same number on VOIP and the simcard, and when in wifi coverage, I get free incoming and very cheap outgoing calls. Not completely seamless, but works pretty well!