Hi, I have just completed and upgrade of a stand alone UCA running 4.1 to MAS 5.0 with UCA 6.0, also upgraded the MCD from 5.0 to 6.0. Since the upgrade users have trouble intermittently consulting/transferring calls to numbers which have been imported from outlook. They also have difficulty logging in/out and setting make busy codes via the UCA client. They are using aprox 15 deskphones and no softphones. Issues only occurred since upgraded. So far ive "swapped" the MCD software bacl to MCD 5, reverted the UCA back to 4.1, then to 5 then back to 6. A complete rebuild of the server has been done with a brand new server-IBM M4 with 12GB RAM. These 16 phones handle aprox 5k calls per day so its a very busy site indeed operating as a centralised reception for aprox 70 car dealerships across the UK. Issue occurs on all clients randomly, mixture of win XP and 7 all within spec. Also tried uninstall/reinstall of clients.