Jan Janak writes:
I remember that some time ago somebody (Juha ?) told me that it is possible to change some value in the register to disable the realm validation, maybe this would be worth trying (I do not know more details).
i used regedit to set the realm to be the same as the domain name in my sip uri, but i too don't remember the details. today i consider it waste of time to try to use ms products as sip UAs, because the company doesn't seem to care about standards or interoperability.
-- juha