At this rate I should make an Asterisk category! Something I keep running across and forgetting to document is the configuration of the Cisco 1760 as a SIP gateway. Specifically, I have the context set to "from-pstn". I prefer this because it separates it, if such a thing ever becomes important to me. The problem is "from-pstn" doesn't include the internal phones context. So, the incoming call can't search the extensions, finds nothing in the dialplan and returns a busy tone. I simply added the "from-internal" context to the extensions_custom.conf in the "from-pstn-custom" section. Now the incoming call can find the group ringall extension and complete the call.