Hi Larry,
Unfortunately, call in users that haven't join via Web and don't have access number can't identify themselves and will show up in Participant List as "Call-in User_X".
We have an enhancement request submitted for the phone number to show up: CSCum01197 Include Caller-ID as identifier for participants calling into CWMS. Please, share this enhancement ID with your Cisco Account Team so they can work with Product Management to include this feature in future releases.
There is no workaround available for this product behavior.
Kind regards,
-Dejan