Ok... have a customer who wants to hear "ringback" when calling a SIP DID directly to an extension, that doesn't have voice mail. The extension audibly rings at the desk, but the caller doesn't hear any ringback, and just hears silence, and thinks they aren't getting through. Is this something I have overlooked, or that isn't going to be controlled by the SV9100s? Appreciate any help. I've looked through the manual, but can't seem to locate what I need to do.

Are you calling through the auto attendant? If so you need to change 24-02-02.

If not I am fairly certain in SIP the carrier has to send that to the end user. I THINK it's like 180 Ringing message that's sent. If I were you I would check your firewall and do a wireshark capture to see the setup.

Appreciate the help. I've pointed the customer to their SIP provider.