This Recommendation describes the general function of telephone signalling messages and the telephone signals and other information components contained in those messages. The requirements relating to the use of the signalling messages and their signal content are specified in Recommendations Q.723 and Q.724.
ITU-T Q.722 SPANISH-1988 Referenced Document
ITU-T E.260 Basic Technical Problems Concerning the Measurement and Recording of Call Durations*， 1993-01-01 Update
ITU-T Q.101 Facilities Provided in International Semi-Automatic Working - General Recommendations on Telephone Switching and Signalling - Functions and Information Flows for Services in the ISDN - Supplements Study Group XI; 2 pp*， 1989-01-01 Update
ITU-T Q.118 Abnormal Conditions - Special Release Arrangements - Series Q: Switching and Signalling Clauses Applicable to ITU-T Standard Systems - Abnormal Conditions Study Group 11; 8 pp*， 1997-09-01 Update
ITU-T Q.28 Determination of the Moment of the Called Subscriber's Answer in the Automatic Service - General Recommendations on Telephone Switching and Signalling - Functions and Information Flows for Services in the ISDN - Supplements (Study Group XI) 1 pp*， 1989-01-01 Update
ITU-T Q.35 Technical Characteristics of Tones for the Telephone Service -Series Q: Switching and Signalling - International Automatic and Semi-Automatic Working - Tones for Use in National Signalling Systems RECMN E.180; Study Group 2*， 1998-03-01 Update