For people having trouble with gizmo call back, are you connected via wifi or 3g? If wifi, is there another gizmo5 account or even VOIP account connected to this IP. Is your router fairly old? I was at my brothers house and was having all kinds of issues. He had an old router and a gizmo account on an ATA. He updated his router and we play along just fine now.

Epage what problems are you having with gizmo5? I've had mine registered with the sipphone setting and a simple SIP log in and both work great. See if setting up a stun server helps at all. Also if you still know your gizmo account, you can try changing the password. Or if all else fails, use sipsorcery.com to register your gizmo account and log into their sip settings and should function the same.