We have a few extensions setup on our Asterisk/FreePBX box for pre-deployment testing purposes. When I attempt to call an extension, it is invaribly reported to be busy and the call is immediately sent to voicemail. We are using softphones (X-Lite) only at this point. The "phones" are able to connect to the server and report a successful login so I think we are OK as far as the extensions are concerned. We can check voicemail from any of the softphones so I believe them to be correctly setup. What else needs to be configured to allow extension to extension calling on a single Asterisk switch?