No one wants to talk about SIP apps? I haven't seen any good single place discussions. I have tried three so far all over WiFi only (I have no cell service in my house): Fring: Overall this one has been the best as far as call quality. It seems to have a bit of trouble and connecting over WiFi at times though (I can't tell if its the terrible WiFi in the X or the app just yet). Main reason I would prefer something else besides Fring is that it does not show who is calling from my address book. It will only display the numer@sipclient. CSipSimple: This one looks like it has great potential, but as said on the page, it's unstable. I am unable to hear the caller talking when receiving a call. Sipdroid: overall this seems the most stable, but the other caller hears themselves echo (I have tested every setting and cannot seem to fix this). Integrates pretty much perfectly with the address book and dialer. Am I missing some others that are good to try out. My choice would be Fring at this point, but I wish it would show me who was calling from the address book.