The user definitely needs rights to the local registry setting because CTIOS saves the last login and server info to the registry. There is no way to circumvent this. So, you dot specifically have to make them admins. But they need to be powerusers with read/write privileges for the following key
HKEY_LOCAL_MACHINE\SOFTWARE\Cisco Systems\
Specfically CTIOS and CTI Desktop subkeys.
Hope that helps. Please rate posts