When setting up SIP URI forwarding to sip:account@pbxes.org from Flowroute they receive a 404 response, doesn't play ball with them. When calling that same URI from another provider it works flawlessly. When using iptel.org to call it it fails. When forwarding to account@iptel.org and setting voicebox, it works. When forwarding calls to account@iptel.org to account@pbxes.org it fails. What is going on with PBXes, it seems to be the issue here. My carrier was telling me they are not RFC compliant and looking for a TO response rather then the INVITE response. Can someone shed some light on this for me?
