The present invention relates in a general manner to the generation of unavailability messages (MESS.TXT, MESS.VOC) upon a failure to establish a communication. Thus, in a method of communication comprising, on the sending of a call from a calling user (B) to a called user (A), there are provided the following steps: determining (E406), in an address book (100) of the called user, a group of contacts (110) comprising a contact corresponding to the calling user; determining the availability of the called user for the calling user as a function of an availability cue (142) associated, in the address book, with said determined group; in the event of determined unavailability of the called user, generating (E410, E320), for the attention of the calling user, a personalized unavailability message (MESS.TXT, MESS.VOC) on the basis of at least one information cue supplied (130, 142, 144, 146), in the address book, at the level of the group determined.