INTERNATIONAL TELECOMMUNICATION UNION ITU-T RECOMMENDATION SUMMARY Rec. No. : Q.953.1 Title : Stage 3 description for call completion supplementary services using DSS 1 Study Group : XI - Switching and Signalling Version : New Date of adoption : 1992 Notes : CALL WAITING (CW) The Call Waiting (CW) supplementary service permits a subscriber to be notified of an incoming call (as per basic call procedures) with an indication that no information channel is available. The user then has the choice of accepting, rejecting, or ignoring the waiting call. The CW supplementary service allows a subscriber to be notified of an incoming call when a B-channel is not available. The notification is done out-of-band following basic call procedures. The CW supplementary service may be invoked when both the B-channels are in use or when only one B-channel is in use. An audible inband indication may be generated locally by the called customer premises equipment, but no inband tone is provided by the network. To order the complete text of this Recommendation, please use the Order Form for ITU-T Recommendations. An electronic version of this form is available on ITUDOC (Winword 2.0: UPI=ITU-5265; ASCII: UPI=ITU-2488).