[Users] openser, spa9000, etc.

Has anyone had any experience with Openser and a SPA9000 configured as I describe below? I have my SPA9000 registered on one line to my ITSP. Calls out to the ITSP work fine from phones registered to the SPA9000. I have the SPA9000 registered to the Openser on line 2 of the SPA9000, and calls from extensions registered on the SPA9000 can call extensions registered on the OpenSER. I use Openser as a sip proxy with lots of phone extensions (more than the SPA9000 will support). When trying to call from a phone registered on Openser to a phone registered to the SPA9000, I get a 403 Forbidden. Same with attempts to dial out to the ITSP. Am I trying to do something that can't be done, or is it a SPA9000 configuration problem? Thanks for any suggestions, Scott Scott Yagel PacketCall, Inc. syagel(a)packetcall.net