Individual destination information is registered into each character/symbol input key on an operation panel. Upon transmitting data, one of the registered character/symbol input keys is pressed to select a destination. In addition to character/symbol input keys, it is possible to register destinations into selection keys. When one of the selection keys having been pre-assigned for a predetermined operation is chosen for a registration, the registration of the key is denied. The registered destination information can be printed out, by a recorder, as a destination list that associates key names and destination names. The destination information can be displayed on a screen by a display, after a retrieval process based on a specified search condition.