ITU-T T.39

This Recommendation defines the procedures to be applied to allow Group 3 facsimile transmission simultaneously with at least speech and audio communication over the GSTN by making use of the capabilities of recommendations describing analogue or digital simultaneous voice and data transmission (Recommendations V.61, V.70 and H.324). These procedures will allow: - initiation of a facsimile call and enabling simultaneous speech communication during the call; - initiation of a voice call and enabling simultaneous facsimile transmission during the call; - initiation of a multimedia call and enabling simultaneous facsimile transmission during the call. The use of simultaneous voice and fax capability is an option of Group 3 facsimile communication.