Automatic versus User-Controlled Methods of Briefly Interrupting Telephone Calls

Some future telephone services will require that ongoing calls be interrupted briefly so that one of the parties can receive data transmitted over the voice path. For example, the new service Caller ID on Call Waiting (CIDCW) will allow subscribers who are off-hook and engaged in conversation to receive data indicating the name and telephone number of a new caller, but the data transmission will produce a break of approximately 1 s. The question arises, then, as to what method should be used to interrupt calls to transmit data. In an automatic form of CIDCW, data would be sent without user control once there is a new call, producing an unexpected break in ongoing conversations. In a user-controlled form, users would hear a tone when there is a new call and initiate the data transmission by pressing a button. A study was conducted to examine how subjects would react to breaks in their telephone conversations and to determine which form of CIDCW was more favorable. Subjects acting as CIDCW subscribers liked both forms of the service, but they preferred the automatic form, which was also rated as more acceptable and easier to use. Furthermore, compared with the user-controlled form, automatic CIDCW resulted in quick, error-free performance. Subjects acting as the far-end party also favored the automatic form, provided that they heard silence during the interruptions rather than a tone. Generally the automatic approach was found to be the better way to introduce a 1-s break into telephone calls.