Hi Martin,
I hope you are well. After some investigating on the internet I found some links that will assist you with configuring the XML file on your Cisco device. Please see links below.
https://www.voip-info.org/wiki/view/Asterisk+phone+cisco+79x1+xml+configuration+files+for+SIP
Thank you.
Martin Gibson
As the subject says.
How can I setup an old c7911 to work with SIP.
I have managed to download the firmware onto the phone using tftp.
But the xml files have me clueless.