Hello,
Anyone with experience in this?  We have a single number, an external conference bridge number.  When users attempt to dial it, the call runs through our OCS mediation server, and is placed with the cisco gateway.  I see the the call come across the IP telephony gateway.  However, the call is immediatlely dropped, and we see a SIP 603 error, of Declined.  If I dial the same number from my Cisco phone, it works just fine.