[Asterisk-Users] polycom phone IP 500/600 conference feature

[Richard]

Hi,

Has anyone used polycom phone IP500/600's conference feature? I ran into
some issues. 

Polycom is not behind NAT.
Polycom calls pstn number A, (gets two way voice), 
presses conference, (A is put on hold), 
calls pstn number B, (gets two way voice), 
presses conference again, suppose to have all three parties in the call,
polycom and B have two way voice, but polycom doesn't have two way voice
with A.

Has anyone experienced it before? I did some trace. It looks like that
polycom phone stops sending rtp packets to the first call, i.e. A.

Thanks,
Richard