There are several possible reasons a number may not show up:
- The incoming call may be blocked with the Call Display Block feature
- The number of the incoming caller may be unlisted, in which case it may show up on the display as a "Private Number".
- If the incoming call is from a long distance number, the number may not appear due to limitations with the switching equipment in your community and/or the switching equipment or programming in the community from which the call is made.