This invention relates generally to the field of telecommunications and deals more particularly with a method and apparatus by which telephone subscribers can defer incoming calls either until a user selected defer time or for a user selected defer period.
Telephone subscribers often have a desire to avoid being disturbed by incoming telephone calls for a particular time or until a particular time. For example, if a nap is to be taken, ringing telephones can create problems by interrupting the nap. Similarly, a one or two hour television program or other activity is more enjoyable if not disturbed by incoming telephone calls.
Although it is possible to turn off the ringer of many telephones and thus prevent them from ringing, this approach has several drawbacks. First, calling parties are led to believe there is no one present at the premises that are called because the ringback tone is still generated to the calling party and the call is not answered. Additionally, the person who turned off the ringer may forget to turn it back on and it can remain off indefinitely even though this is not intended. Another problem is that emergency calls as well as routine calls do not ring through, and the emergency caller has no way to complete the call.
The present invention is directed to a call deferral method and apparatus that can be implemented either at the premises of a telephone subscriber or at the central switching office of the telephone company. In accordance with the onpremises implementation of the invention, a call deferral device receives power from a standard electrical outlet, and it may be plugged into a telephone jack. The device includes an interface circuit that acts to the telephone central office the same as a telephone set. In normal operation when the device is not in the defer mode, incoming calls are treated in the usual manner the same as if the device were not present on the line.
It is an important feature of the invention that the deferral device is not dedicated to any particular telephone set but instead can be addressed and programmed from any telephone on the subscriber line. The device receives DTMF signals entered from the key pad of any of the telephones on the line. If the DTMF entries represent outgoing calls, (i.e., the only key pad entries are on the 0-9 digit keys on the key pad), they are ignored by the device and the outgoing calls can be completed in the normal fashion. However, if one of the special function keys (the * or # key) is entered, the device detects command entries and verifies that the commands represent valid instructions to enter the defer mode.
It is another special feature of the invention that the user can make defer commands that are commands either for a specified defer time (i.e., defer calls until the defer time such as until 3:00 p.m.) or for a specified defer period (i.e., defer calls for the duration that is entered such as for a period of one hour). The device keeps track of the time of day and, in the case of a valid defer period entry, computes the defer time by adding the specified defer period to the current time of day. In both command entry modes, commands are entered in a simple manner by depressing appropriate digit keys, specifying the defer period or defer time followed by the * or # key to specify whether the defer period mode or defer time mode is selected.
When the device is operating in the defer mode, incoming calls are deferred until the defer time, and normal operation (i.e., no deferral of calls) automatically resumes at the defer time. In the defer mode operation, the device detects a valid ring signal, suppresses the telephone ringers, seizes the telephone line and transmits to the calling party a synthesized voice message indicating the telephone number of the called party, the fact that calls are not now being accepted, and the defer time after which the call can be repeated without intervention.
Thus, the user can select either the time at which he desires for call deferral to end or the period during which it is to be in effect. In either case, programming can be carried out from any telephone on the line with a minimum of key entries required. Calling parties are informed of the fact that calls are being deferred at the request of the called party and are also informed of the time at which the deferral period ends.
Callers having a special access code can override the deferral of calls in emergency situations by entering the access code on their telephone key pads after receiving the deferral message. The access code entry interrupts the defer mode for a one minute period so that the call can be repeated and passed through normally. Consequently, if an authorized possessor of the access code must complete the call because of an emergency, he can do so by overriding the deferral.
The call deferral can be implemented in much the same manner in the telephone central office. The central office implementation has the advantage of making use of hardware that is already present in the central office. Also, incoming calls made during the defer time are not completed but are instead intercepted at the central office of the called party. Consequently, the billing sequence is not completed and there is no toll charge for long distance calls attempted during the deferral period.