GB2297455A

GB2297455A - Automatic call divert for cordless telephone system

Info

Publication number: GB2297455A
Application number: GB9501698A
Authority: GB
Inventors: Anthony J Wray; Gary John Aitkenhead; Chris Flain
Original assignee: Motorola Ltd
Current assignee: Motorola Solutions UK Ltd
Priority date: 1995-01-28
Filing date: 1995-01-28
Publication date: 1996-07-31
Anticipated expiration: 2015-01-28
Also published as: GB2297455B; GB9501698D0

Description

AUTOMATIC CALL DIVERT FOR CORDLESS TELEPHONE SYSTEM Field of the Invention This invention relates to cordless telephone systems and more particularly to the diverting of calls in such a cordless telephone system.

Background of the Invention Cordless telephone systems include Cordless PBX (CPBX) systems or cordless public access systems. Typically such cordless telephone systems include a plurality of cordless (radio) handsets or Cordless Portable Parts (CPPs) and associated Cordless Fixed Parts (CFPs). The Cordless Fixed Parts (CFPs), also known as Radio Fixed Parts (RFPs), are (radio) cordless base stations. The cordless base stations are typically sited in an office environment in the case of Cordless PBXs or in a public environment in the case of public access systems.

The Cordless Portable Parts are essentially low power cordless telephone handsets, and the CFPs or RFPs are the associated cordless base stations, providing connection through a centrally integrated telephone switch to the wired services (e.g. PSTN or ISDN). In general, such telephone switches transmit and switch the voice traffic digitally, and are computer controlled. Examples of these types of cordless telephone systems include CT2 (second generation cordless telephones) and DECT (Digital European Cordless Telephone).

Modern cordless telephone systems such as CT2 and DECT typically offer more functionality than earlier cordless telephone technologies. The intelligence in modern cordless telephone systems resides primarily at the cordless telephone handset with the cordless base station frequently performing a repeater (call routing) role. Early cordless telephones were generally available as a "matched pair", where a cordless handset and its cordless base station were hard-coded to each other. Thus a cordless handset could only communicate via one associated cordless base station.

In modern office telephone systems a number of cordless telephone base stations and fixed telephone terminals can be connected to the wired services of PSTN or ISDN via the centrally integrated switch. Users can therefore choose the most appropriate telephone units for their application.

One problem associated with the cordless telephone system arises from the limited range of the cordless portable part due to its low transmit power. The problem manifests itself when the cordless part is taken outside of the cordless base station's coverage range and is therefore no longer able to receive calls from the cordless base station.

In this situation the cordless base station will continue to ring and page the cordless handset until the cordless handset responds.

It is therefore desirable to have a method for automatic call divert in a cordless telephone system when a cordless handset is out of coverage range of the cordless base station.

Summarv of the Invention According to the present invention, there is a method provided for an automatic call divert in a cordless telephone system having at least one switch connected to a cordless base station for communication with a cordless handset, including the steps of programming a preferred recall number in a memory element of the cordless base station, transmitting a ringing signal to the cordless base station from the switch, ringing the cordless base station and diverting the call to the preferred recall number when no response is forthcoming from the cordless handset.

Brief Description of the Drawing FIG. 1 shows a block diagram of a communications system operating cordless and fixed telephone systems.

FIG. 2 shows a flow diagram illustrating the method of call divert for the preferred embodiment of the invention.

Detailed Description of the Drawings Referring first to FIG. 1, a block diagram of a communications system is shown. The communications system comprises a switch 10 operably coupled to a number of fixed telephone units 40, 42 and 44 and cordless base stations 20, 22, 24 each having at least one memory element 25, 26, 27 and each telephone unit respectively capable of providing signals to and receiving signals from cordless handsets 30 and 32.

In operation the switch 10 routes incoming telephone calls from the PSTN or ISDN to the fixed telephone units 40, 42 and 44 or cordless base stations 20, 22, 24. When a cordless base station 24 receives an incoming call the cordless base station 24 rings and transmits a paging signal to the appropriate cordless handset 32 on a radio channel. The cordless handset 32 continuously scans the radio channels for the paging signal. The call is set up on the radio channel when the cordless handset 32 responds to the paging signal transmitted by its cordless base station 24.

Referring now to FIG. 2, a flow diagram is shown illustrating a method of call divert according to a preferred embodiment of the invention. In the preferred embodiment the cordless handset 32 is out of range from the cordless base station 24 of FIG. 1. The switch (or PABX) 10 receives a call request for the cordless handset 32 as in step 100. The switch 10 sends a ringing signal to the appropriate cordless base station 24, step 102. The cordless base station 24 detects the ringing signal and begins to ring as in step 104. The cordless base station 24 then pages the cordless handset 32 on a radio channel, step 106, and waits for a response from the cordless handset 32 as in step 108. If a response is received the radio link is established and the call communication continues with the normal call procedures as in step 110.If the cordless base station 24 receives no response from the cordless handset 32, due to say, the cordless handset 32 being out of range, the cordless base station 24 sends an off-hook (engaged) signal back to the switch 10, step 112, immediately followed by a recall signal and the preferred recall number of the cordless handset 32 as in step 114. The preferred recall number is previously stored in the memory element 26 of the cordless base station 24. The switch 10 then diverts the call to the preferred recall number of the cordless handset 32, and the cordless base station 24 returns to an on-hook state as in step 116.

Although the preferred embodiment is described as requiring the preferred recall number being previously stored in a memory element 26 of the cordless base station 24 it is within the contemplation of the invention that the preferred recall number is available elsewhere, for example from the caller or the system.

Advantageously the cordless handset 32 programs the preferred recall number over-the-air to the cordless base station 24 and the preferred recall number is stored in the memory element 26 of the cordless base station 24.

Thus, a method for automatic call divert in a cordless telephone system is shown. Advantageously, the user of the cordless handset 32 can arrange for the call to be diverted to an answering machine, a fixed telephone unit 40, 42, 44 or an alternative cordless base station 20 or 22, without losing the call.

Claims

1. A method for providing an automatic call divert in a cordless telephone system having a switch connected to a cordless base station that communicates to at least one cordless handset, the method comprising the steps of: programming a preferred recall number in a memory element of the cordless base station; transmitting a ringing signal to the cordless base station from the switch; ringing the cordless base station and paging the at least one cordless handset; sending an off-hook signal and the preferred recall number for the at least one cordless handset from the cordless base station to the switch, when no response is forthcoming from the at least one cordless handset; and diverting of the ringing signal by the switch to the preferred recall number.

2. The method of claim 1 further comprising the step of returning the cordless base station to an on-hook status.

3. The method of claim 1 wherein the switch is a standard PABX system.

4. The method of claim 1 wherein the step of programming the preferred recall number in the memory element of the cordless base station is performed by the at least one cordless handset.

5. The method of claim 1 wherein the cordless base station and cordless handset operate on a cordless telephone system.

6. The method of claim 1 wherein the at least one cordless handset continuously scans for a transmitted paging signal when not in a call communication.

7. A method for providing automatic call divert substantially as herein described with reference to FIG. 2 of the drawing.