Books ordered by phone and delivered by mail is the new service offered to library users by the San Antonio Public Library System. Requests sent in by letter are also honored, although activity of this type is negligible. The program is designed to update library service, to better serve the shut-in, and to reach those who are not now regular library users. Book loans through the mail average approximately one percent of all loans made--24,000 annually from a total of over 2,100,000 loans. The average cost per book, based on long range calculations, is 16.5 cents. (MF)