There is a closed thread that has the exact same problem I am having, Cisco 7841 IP phone has fast busy as soon as digit is dialed. The thread referenced indicates the solution “was missing the version number at the top of my Dialplan”. What version number are they referring to and how is the version number tagged in xml in the dialplan.xml file? I’ve looked for examples and can’t find any. Unfortunately the dialplan.xml referenced in the thread is missing.
Solved. It actually was not the need for a version number, which I realized was <?xml version="1.0" encoding="UTF-8"?>
duh!
I had copied my dialplan.xml from a webpage and many of the characters were not the correct character set (i.e. quotes, periods, dashes, etc.) Once I fixed those and tested by removing the version tag the phone dialed as it should.