ng to SIP to work right. I started this project on CME 3.3, and everything worked fine. By the time I was done with multiple SIP trunks, I had gone from CME version 3.3 to 4.0 to 7.1 to 8.0, where it finally all worked. The main driver for this was having dual SIP trunks actively registered to the same provider. That's likely not a requirement for many people, since, depending on your service, you may be able to send and receive multiple calls at once on a single SIP trunk (unless you need multiple inbound numbers). A more likely scenario is to have two SIP trunks from different providers for diversity and/or redundancy. If these trunks were from different providers, we'd have multiple realms configured. One of the benefits of running on CME 8.0 and later is the ability to include the number keyword in the credentials command. The problem I discovered with my pro- vider was that if I actually included the phone number, the trunks wouldn't register properly. I needed to add the username into the number field to make it work: R1-PBX(config-sip-ua)# credentials number 608222222 username 608222222 password 123456789 realm voip.sip-provider.com R1-PBX(config-sip-ua)# credentials number 557333333 username 557333333 password 7 123456789 realm voip.sip-provider.com Again, different providers may deal with this differently, SO you might have to play around to determine what works best for your situation. see if your credentials worked, use the show sip-ua register status command: R1-PBX#sho sip-ua register status expires (sec) registered P-Associated-URI 20001 20002 20003 20004 557333333 608222222 The way I've designed this system, the SIP trunks will be used only for communication outside the office. Thus, the phones do not need to register with the SIP provider. By default, they will try and, depending on how your SIP provider is configured and the type of service you've bought, they may very well succeed. I don't want that to happen, SO I'm going to prevent it by telling each ephone-DN not to register with SIP. To prev