i searched and couldnt find this issue... when i receive a call through gizmo on my tablet (which is set up through grandcentral) , when i answer the call , sometimes i get no sound on my end but the caller can hear me.
this also happens when i make a call out from my tablet using the grandcentral dialer app. the whole problem seems to be intermittent , im just wondering is it an issue with my tablet , my connection , or the grandcentral or gizmo servers????

The most common reason for this is NAT at your router. Even though your call has passed the incoming call setup it can still be the router not setting up the RTP channel for actual voice. Some would suggest port forwarding but I don't like doing that and it is rarely required except when the actual server is behind a NAT. And this doesn't help when you are at random WiFI locations.

With your setup the call is doing extra steps so it could be a problem outside. Some systems will try to do a "reinvite" so that the PBX doesn't have to take the load but that can be troublesome with SOHO routers sometimes.

I use my NIT phone everyday and have seen the same problem on rare occasion. I'm often on the same LAN as the server so NAT isn't the problem in my case. My desk phones (also SIP) don't have this problem. My guess is that the NIT isn't setting up the outbound RTP channel sometimes and in my case it seems to be tied to the NIT having to shutdown whatever media player I have running at the time and answering the call. The call is answered and the other party can hear me but I don't hear them. I have found that if I leave the internet call app minimized it doesn't happen . Right now I'm calling this a bug that happens if the NIT can't setup the outbound voice channel fast enough.

itjust seems to me , like you said , the tablet isnt responding fast enough. i do remember that if i have pidgin open when i make/receive a call i get no sound , but typically this issue occurs when no other program is running.. at least not in the foreground anyways

I have this problem every nowe and then. I have found lowering and raising the volume will make the audio kick in.

Or its just a coincidence.

You should try and determine if this is a GC issue/interaction issue. Do you have any phones you can backdoor dial and then call back through the caller id number?

similar problem here. GC calls my Gizmo and asks me to accept. I press the '1" button and then I can't hear anything and the other person says they get cut off or sent to voicemail.

lanrat... your solution worked.....ive been testing off and on since u posted that... my fiancee threatened to put the phone somewhere unpleasant if the phone rang again LOL