I know in the SL100 world it is ANA, Automatic Number Announcement. We always had one in our switch;
In using Google some, if they are DID's:
"One such toll-free service is one owned by MCI - 1-800-444-4444. This number is easy to remember and, when called, will read back your number after a very short message.[2] It is noteworthy that a suspended or out of service line or an incoming only line would not be able to reach any toll-free numbers.