This issue has been resolved.
As a result of upgrading to 3.0 from 2.4 the TUI user login process (stations and voice mail) apparently changed. In the specific case where a user logged logged in with a four digit extension, say 9876, but another extension existed that had only three digits, say 987, the system required the password to be entered a 2nd time in order to choose between the two extensions. We had three digits extension from our old phone system mapped for conversion purposes that duplicated the first 3 digits of new 4 digit extensions.
Thank you for your replies in this thread.