TELEPHONE ANSWERING SYSTEMThis invention relates to a telephone answering system for use with a total access communication system (TACS), extended TACS (ETACS) cellular radio telephone network and/or newer systems such as GSM.
Formerly, to connect an answering device to a radio telephone network, it has been necessary to use a socalled "line emulator" which is connected to the telephone equipment at the receiving site. By providing a connection equivalent to a conventional socket for a land telephone, the line emulator allows a conventional telephone answering device to be connected to the radio telephone network. Such an arrangement has several disadvantages.
Firstly, the need for a line emulator adds significantly to the cost and complexity of connecting an answering device. Furthermore, such an arrangement is entirely unsuitable for a personal telephone of the type that may be carried in a pocket or the like, and even when installing such an arrangement in a vehicle, space and cable routings are often important considerations and thus the mounting and connection of a line emulator and an answering device, in addition to the units required to interface to the telephone network, may prove difficult.
In addition, a conventional answering device is unlikely to have been optimised for mobile use and thus will not be particularly small nor robust, nor will it necessarily be easy to power from a d.c., battery power source which may only have a small capacity. Furthermore, since most, if not all, conventional answering devices rely on an analogue tape system for message storage, such devices are not suited to operation in a harsh environment such as that found in a moving vehicle, which is typified by vibration, wide temperature variations and severe electrical and radio frequency interference.
An alternative system that has recently been implemented by radio telephone network operators, in the United Ringdom at least, permits calls to be stored centrally.
Call storage commences when a user notifies the operator that he is no longer available by radio telephone. When the user returns, he can call the operator and request that any stored messages are replayed to him over the air. Whilst such a system overcomes certain of the above disadvantages, it is inflexible and it requires the user to expend air time to listen to any messages. In addition, a periodic subscription fee is charged for use of the service.
It is an object of the present invention to overcome at least some of the disadvantages of prior telephone answering systems by providing a compact, robust system that obviates the need to transmit stored messages over the air.
According to the invention, a telephone answering system for responding to an incoming call received via a TACS and/or ETACS cellular radio telephone network, comprises voice encoding means comprising audio input terminals for coupling to an audio input system and telephone input terminals for coupling to the telephone network, and for generating digital voice data from at least one input audio message received via the telephone input terminals and/or the audio input terminals, voice storage means coupled to the encoding means, for storing the digital voice data, voice decoding means comprising audio output terminals for coupling to an audio output system and output telephone terminals for coupling to the telephone network, and coupled to the storage means for receiving the voice data from the storage means and for generating at least one output audio message from the voice data, for transmission via the output telephone terminals and/or replay via the audio output terminals, and tr means coupled to the encoding means, the decoding means and an operating keypad having at least one operating key, and comprising control telephone terminals for coupling to the telephone network, the control means being operable to (a) cause the decoding means to generate at least output message and to transmit it via the output telephone terminals in response to the start of the incoming call, (b) cause the storage in the storage means, of voice data generated by the encoding means from any subsequent input message received via the input telephone terminals, and (c) upon receipt of an operating command from the operating keypad, cause the decoding means to generate at least one output message and to replay it via the audio output terminals.
sThe system is typically implemented as a stand-alone unit which is inserted in a cable between a radio telephone transceiver and its associated handset. The system may operate in two distinct modes selected using the operating keypad.
In a first, "transparent" mode, all signals between the transceiver and handset are passed through unaltered and the transceiver/handset combination is allowed to operate as a conventional radio telephone.
In a second "answer" mode, the system may operate to take control of the transceiver by emulating the control signals that would normally be generated by the handset and/or the transceiver i.e. by generating transceiver signals of the type which would normally be generated by the transceiver to control the handset and conversely by generating handset signals to control the transceiver.
Having taken control of the transceiver, it may be used to couple the encoding, decoding and control means to the telephone network. Also, the microphone and loudspeaker housed in the handset (or fitted to the vehicle in a hands-free implementation) may be used by the encoder and decoder for message reception and replay.
Alternatively, the system may be incorporated in one of the units conventionally required in a radio telephone installation; the transceiver unit, for example. The answer mode is then offered as a factory-installed option with activation from the handset.
As a further alternative, the system may be designed for use with a hand-portable cellular radio telephone. This may be achieved in several ways: (i) by providing a plug-in module which clips tothe base or back of the phone and which makesuse of connection terminals provided on thephone.
(ii) by incorporation of the system into a standalone base unit into which the phone isinserted.
(iii) a stand-alone base unit as in (ii) above butalso incorporating a battery charger for thephone battery.
(iv) by incorporating the system in a device whichmay be interposed between the phone and a socalled hands-free car kitThe voice storage means is preferably an integrated semiconductor memory (such as RAM and/or ROM) and is used for storing a personal announcement or "out-going message" (OGM) for transmission in response to the start of an incoming call, and for storing any incoming messages. This in conjunction with an integrated semiconductor CODEC comprising the encoding and decoding means with if required, external amplification and buffering of the input and output messages, permits the system to be made without moving parts. A system made in this way can be more reliable and more compact than a mechanical system using magnetic tape storage.
The operating keypad preferably has no more than two keys. It may be housed separately from the other components of the system, allowing the keypad to be placed at a location convenient for the user, whilst the other parts of the system may be placed out of sight, in a vehicle boot, for example.
Preferably in answer mode, the handset display is used to show status information such as the number of incoming messages that have been stored. At least some of the keys on the handset are preferably disabled, at least to prevent the user accidentally switching the radio telephone off. Such action would switch the transceiver off which would prevent the system from transmitting or receiving via the telephone network.
The invention will now be described by way of example with reference to the drawings, in which :Figure 1 is a schematic diagram of a system in accordance with the invention, installed as part of a radio telephone installation;Figure 2 is a block diagram of the system of Figure 1;Figure 3 is a flow chart of typical user operations upon initial entry to a vehicle to initialise the system ofFigure 1; andFigures 4A and 4B form a flow chart of typical user operations when returning to a vehicle equipped with the system of Figure 1 (Figures 4A and 4B are intended to be laid end-to-end).
The system described below may be used in a vehicle but can be adapted for use with a personal telephone or in other mobile automatic answering applications.
With reference to Figure 1, a system in accordance with the invention comprises, a main unit 2 connected in a cable 4a, 4b that would conventionally run directly from a radio telephone transceiver 6 to a handset cradle 8.
Connected to the cradle 8 is a handset 9.
The transceiver 6, cradle 8 and handset 9 may already be installed in the vehicle as part of a radio telephone installation, in which case the only required electrical alteration to the installation is disconnection of the cable between the transceiver 6 and the cradle 8, this cable then being used as either cable 4a or cable 4b inFigure 1.
The main unit houses an interface printed circuit board (PCB) 10 which interfaces with the handset cradle 8 and the transceiver 6, and a system PCB 12 which controls the answer functions. The interface PCB 10 is tailored to accept and generate the signals of a particular transceiver/handset cradle combination and would be different for each type of installation. The other parts of the system are common for all installations.
The interface PCB 10 can be made to operate in a "transparent" mode wherein signals are passed between the transceiver 6 and the handset cradle 8 without alteration, allowing normal operation of the radio telephone. The interface PCB 10 can also be made to operate in an "answer" mode wherein it emulates a transceiver/handset combination in order to take over control of the transceiver 6 and the handset 9.
Also connected to the main unit is a control head (or keypad) 14. This has an "On/Off" key 16 and a "Review" key 18. The keys are non-latching push buttons and each has a LED mounted in its visible face. Key 16 has a green LED 16a and key 18 has a red LED 18a which are used to indicate status information. In an alternative embodiment, LED 16a and LED 18a are mounted in the panel surrounding the keys. The control head 14 is designed with only two buttons and may, therefore, be very compact, and can be mounted within reach of the vehicle's driver, whilst the main unit may be mounted elsewhere in the vehicle.
The handset 9 has an LCD display 22 and a keypad 24. In answer mode, status information is made to appear on the handset display 22 and the keypad 24 is partially disabled. In particular, the display 22 is used to indicate that the system is in answer mode and to indicate how many incoming messages have been stored.
Also, a "call-screening" feature is provided whereby the user may interrupt ("break in") the storage of an input message. This feature operates in one of two waysi) In answer mode, the system will automaticallyanswer the phone after a preset number of rings (forexample after the second ring). If the user liftsthe handset (or presses Send in a hands-freeimplementation) before the system has answered thephone, answer mode is temporarily disabled and theuser may speak to the incoming caller in a normalmanner. Upon replacement of the handset, the systemautomatically reverts to answer mode.
ii) If the system has already answered the call, itmay be disabled using the key 16, thereby puttingthe system in transparent mode. The user may thentalk to the incoming caller in a normal manner.
With reference to Figure 2, mounted on the system PCB 12 are a CODEC 26 which is connected via buffers 28a, 28b, 28c, 28d to transmit and receive input lines 30, 32 and transmit and receive output lines 34, 36. These lines are connected to the interface board and carry the audio signals that would usually pass directly between the transceiver 6 and the handset cradle 8. The CODEC 26 uses a sample rate of 32Rbits/s and can operate to encode audio signals present on lines 30 and 32 in order to store an OGM or to store incoming messages respectively.
It can also operate subsequently to replay these messages via lines 34 and 36 to permit the user to hear messages, to review a stored OGM (via line 36), or to replay theOGM over air, via line 34. Alternatively in transparent mode, the signals on lines 30 and 32 are passed directly through to lines 34 and 36 respectively.
Connected to the CODEC are control means implemented as a RISC microcontroller 38. Associated with this is a dynamic RAM block 40 which is used to store voice data for encoding and decoding by the CODEC. The control head 14 is connected to the microcontroller 38. A control bus 42 runs between the microcontroller and the interface PCB 10 and serves to control the operation of the radio telephone line protocols and to enable the emulation of the handset/cradle combination.
The microcontroller 38 coordinates the functions of the system in both "answer" and "transparent" modes. TheCODEC incorporates an automatic voice detection feature which operates by monitoring the audio level on lines 30 and/or 32. When the level drops below a predetermined threshold, a flag is set. The flag is monitored by the microcontroller 38 which terminates recording of a message (incoming call or OGM) when no voice sound is detected for more than 2 seconds. This serves to conserve storage capacity. Additional functions of the system are summarised in the flow-charts of Figure 3 andFigure 4.