The name and phone number displayed in the Incoming Call Pop-up are obtained from the information that is sent along with the phone call. This is the same information used to display information on phones with Caller ID. There are a number of reasons that the Caller-ID information may not be available to ICM. If the call came from certain cell phone networks, or was initiated from a telephone network that does not support Caller ID, that indicates that the call reached our server with no information to display. In some of these cases, ICM displays values of Unknown or Unavailable, while in others, callers may be asked to enter the missing information.
If you have defined nicknames for common callers, the nicknames will be displayed in the Incoming Call Pop-up instead of the caller name. For details on nicknames, refer to Providing Nicknames for Common Callers.