I have bought a Cisco 8841 IP Phone which has SIP firmware installed, I have managed to set up the phone with the SEP<mac>.conf.xml on the local network however I would like to connect the phone to a remote asterisk server. I have tried to add a domain name which resolves to the IP of the asterisk server with the chan Sip ports open. I have used TFTP to send the XML file to the phone however the phone just says "Phone is registering" and does not work. I have then connected a DD-WRT router that connects to my home using PPTP and through the network, the phone is on, the asterisk server can be connected on phone. I have also managed to connect a softphone to the asterisk server through the VPN however the phone still says "Phone is registering". No issues are shown about connecting to the asterisk server can be found on the web GUI or on the phone itself. I understand that connecting to an asterisk server is not supported by Cisco itself so I am unable to contact them regarding the issue. Has anyone has this problem before? or knows how to connect a Cisco 8841 to a remote asterisk server using Chan SIP TCP?