Further research and lab testing has led me to believe that BroadVoice is denying SIP calls from CME because CME generates too much traffic by trying to register every configured extension with the provider SIP server. I have 10 extensions configured...

Yesterday I configured CME 3.2 to use a SIP trunk to BroadVoice. At this point it is working for inbound calls only. Outbound calls are getting a "404 Not Found" error. Here's the pertinent section of the config at this point:dial-peer voice 10 voip ...