[cisco-voip] One way communication for IP phones

[Yunming Song]

Hello Group,

We have 2 sites, one in rockville and one in herndon.  All telephony servers 
and approx 100 IP phones are located in herndon behind a pix firewall.  Our 
rockville location also has several IP phones behind a pix firewall.

In herndon, we are running CM 3.3(4)sr2, and Unity 4.0(4).

In herndon, all IP phones can call each other as well as place outside calls 
and receive incoming calls.
In rockville, IP phones can call IP phones in Herndon no problem.
When IP Phones in Herndon call IP Phones in rockville, the rockville phone 
rings, but when the user in rockville picks up the receiver, the call 
terminates.  The same thing happens when rockville users try to call each 
other internally.

Any idea is pretty much appreciated.

thanks a lot,
Yunming Song
(571)323-5030