You'll need the IP address of the specific Vonage SIP proxy server set up for that account. It should be part of the account paperwork, or I guess you could get it from Vonage tech support (no idea how painful that might be).

Is it a Cisco ATA 186 adapter? If so, you can view the status and change configuration via web browser. The trick is finding the IP address of the adapter on the internal network. Shoudn't be too hard, but if all else fails, pick up the phone and then press the "Function" button on the Cisco. You'll hear "Configuration", then key in "80#" and the adapter will read off its IP address.

Armed with that, you can explore adapter's the web interface and discover the SIP server's IP for further testing.


-Steve