It is suggested that telephonists use the redundancy in telephone numbers in order to remember them more efficiently. A group of eight telephonists from the York area are tested with nine-digit numbers made up of real five-digit telephone numbers preceded by a four-digit area code. Randomised into the same memory test are other nine-digit numbers constructed by randomly permuting the telephone numbers. A control group of eight participants who are matched for age and social class but are not telephonists is tested with the same material. For each participant, serial recall scores out of 100 are recorded for telephone numbers and random sequences.