[Serusers] wm 4.7 / subscribe error message 500

dear all, have been away from 'SIP' for some while and looking to progress from where i had left off i am endeavouring to use Windows Messenger 4.7 (on XP) and where before i was able to get functional system of two WM clients with iptel.org registrations to communicate fully this is no longer the case am still using WM 4.7 but now on Windows XP (if this should make a diff ??) the register messages seem to complete ok but fail when i add contacts to my list - the packet capture indicates a "500 unsupported" message back from the iptel server in response to the SUBSCRIBE message it seems there has been some maintenance of the iptel server which late last week reported in the capture Sip Express router 0.8.14 we know have 0.8.99-dev-tls2 TIA GT