IP Office Softphone will not work if logged onto windows domain

[cbrend]

Strange one. Cannot find a particular setting in a domain security policy (we use group policies) that would affect this. However, if I use a pc/laptop and logon to the DOMAIN, even as a domain admin account, the softphone will let you login and attempt to launch...you see the physical phone log itself out...but the softphone application on the pc/laptop never actually starts. We have to kill it with taskmanager.

If i take the same pc/laptop and logon to it as a LOCAL user account, not to the domain, softphone works fine.

Oh, and this is consistent across multiple pc's/laptops. Identical behavior on all of them. I've had to modify the Softphone desktop shortcut to "runas \USER:localaccount...." but that is causing us to create a local account, and the user has to remember the password for it (won't let me use a blank password for the local account). further... because the pc is a member of the domain, all passwords (local or domain) must meet complexity requirements. so now the user has 1) domain logon password 2) softphone application logon password 3) local user account password.

Any suggestions? Thanks!