Zero1: Your assumption makes sense for the iDen version of the PTT service, which is RF based (commonly known as a walki-talkie) which is basically an 800mhz trunked radio system (the version that ‘Nextel’ uses). However, I imagine (wild guess – honestly have no clue) that Cingular has deployed the TCP/IP version of this, which encodes your voice and sends it over the network to the recipient. This makes sense considering their current investment in the EDGE network. Either way - should be interesting to see how this develops.