All, Im all backed up to flash gingerbread, but do not really understand how SIP/VOIP works. Hopefully someone can clarify the capabilties of the SIP calling in 2.3. I would like to know if its possible to call landlines for free with the combination of a pbex account, google voice, google voice call back. Can I call out to land line with GV, set google voice call back to redirect to my Pbex account, PBex account directed to call my google voice number, which inturns connects my cell with my original dialed number? Thanks in advance.