If a user has a DID number or extension assigned to them and they cannot receive calls through that DID number or extension, check the following:

• If the user has both a DID number and extension, the DID number and extension are entered as different phones in the user’s Contact Information section in their profile. The DID number and extensions are considered different numbers and cannot be entered as the same phone. See Set your contact options.
• The DID number and extension are listed and defined in the DID or extension pools. 
• The user has the proper license type, roles, and permissions. See Check a user’s permissions.