GB2163319A - Telephone traffic measurement - Google Patents

Abstract

Traffic measurement, especially in a PABX, is effected by radio to avoid interference with the installation. To do this each line has a telephone set unit with an inductive sensor (1) which detects all connection attempts, whether outgoing or incoming and stores information relating thereto in a store 3. A block of such telephone units are polled, e.g. once per 10 seconds, by radio from a command unit, where the addresses of the lines served are repetitively generated by an address generator and sent by radio to the telephone set unit. Each set unit responds to its address and if its store (3) contains details of a call which has been completed, that message is sent to the command unit. Here it is decoded and stored in a store unit, from which such messages are sent typically via a modem and switching equipment to a central traffic analyser. In a large PABX a number of such command units each serving a block of lines is used. <IMAGE>

Description

SPECIFICATION Telephone traffic measurement This invention relates to traffic measuring apparatus for use in a telecommunications system.

According to the invention there is provided traffic measuring apparatus for monitoring call establishment at a defined point in a telecommunications system, which includes a sensor associated with but not in physical contact with the transmission medium at the defined point, which sensor responds to conditions at the defined point relevant to call establishments involving that defined point, storage means associated with the sensor in which information relative to said call establishments or attempts therefor responded to by the sensor are stored, and a radio transmitter associated with said storage means and adapted to transmit to a remote point, when required, measages each of which identifies the defined point and includes details of call establishments extracted from the storage means.

In a practical application of such apparatus, e.g. in a PABX, a number of apparatus units each of the type set out above are used, each located at one of a number of defined points.

These defined points may be telephone subscriber's stations or the exchange line circuits for those lines, or in fact any other traffic handling points. The sensors are inductive devices in the system to be described, but other sensing techniques can be used. These circuits can be caused to transmit their traffic information messages when required, e.g. in response to request messages from a command station, or can be each caused to send at a specific time, different such times being used for different ones of the defined points being monitored.

An embodiment of the invention will now be described with reference to the accompanying drawing, in which Fig. 1 is a highly simplified block diagram of an apparatus unit for use at a defined point such as a subscriber's telephone, and Fig. 2 is a highly simplified block diagram of a command unit such as used to advise a central point at which traffic information is collected and handled as required.

Both of the units illustrated in the drawing use radio transponders which can be similar to the radio pager transponder described and claimed in our Patent Specification No.

2083977 (I.A.W. Vance 7). This, as will be seen below, is used in conjunction with inductive sensors which can recognise off-hook conditions, Strowger and MF signalling without direct electrical connections to the telephone handset.

The transmitter-receiver complex and associated electronics, Fig. 1, is in a plastics case and is battery powered. It includes an inductive sensor adjacent to or otherwise in association with the line at the telephone station so that it can respond to changes in the line conditions. Its operation, and the passing on of the information it collects, are controlled by pulse shapers and counters in the block 2.

From here the information passes to storage means 3, which in one case has a capacity of 30 bytes of data, for each incident such as off/on hook, "dialled" digits, duration etc. It can also include information in respect of off hook/on hook condition for incoming calls, which is useful where reconciled patterns of network behaviour are required.

The stored information is supplied to a radio transmitter 4 from which it is transmitted to a remote unit, such as shown in Fig. 2. This transmission is normally done in response to a polling signal from the remote unit, which is received by radio in a receiver 5 the output of which goes to a block 6 which includes an address decoder which responds to a polling signal identifying the line to which the unit is attached. The block 6 also includes a scan counter and other circuitry needed to cause the transmission of the current contents of the storage means 3.

Both outgoing and incoming call establishment is registered and the rate of polling of the telephone set units is sufficiently rapid to ensure that all normal usage is detected.

The command unit, Fig. 2, includes a real time clock 10, which drives a scan counter 11 to perform the polling. That latter drives an address generator 1 2, which supplies successively the addresses of the lines to be monitored. It also controls a decoder and store 1 3 which will be referred to below. The addresses are sent out successively by a transmitter 14, which can be similar to the transmitter 4, Fig.

1.

In the gaps between the addresses sent by the transmitter 14, any messages from the remote units are received, each such message occurring just after the address was sent.

Such a message is received by the receiver 1 5 whose output goes to the data decoder/ store 13, where the message is stored with the address of the line to which it relates. The store 1 3 has accommodation for a number of such messages, which may for example be subsequently sent out via a modem 16, which includes an auto-dialler which dials the number of the central traffic analyser, the messages in the store can then be sent via the switch 1 7 to that analyser. Alternatively this could use a radio link, e.g. one similar to that used from a telephone set unit to a command unit.

As used in a PABX, the telephone set unit responds to its own interrogation code from a command unit, and transmits in return to such a unit located typically within 75 metres.

As described above a return message is only received if the polled unit had in its store a message to be sent. It is also possible for a telephone set unit without a message to be sent to send a "nil return" message. This method has the advantage that the units associated with the telephones are continuously checked.

Where the system is used in a large PABX, several command units, each serving a block of-lines, may be provided, e.g. one for each of a number of floors in a multi-storey building.

These command units may be then served by a single central traffic analyser. The codes and possibly frequencies used are so chosen that interference does not occur when multiple command units are operating in adjacent but discrete systems.

The interrogation rate of the receivers at the line units is such that all traffic generated in normal use is detected, and for this purpose a call set up time of 10 secs. has been assumed, with a typical holding time of several minutes. A transmitter, in the system actually described, does not respond to send a message in respect of a call at its telephone set unit until the telephone has returned to its onhook state. The scan control circuitry counts intervening scan cycles to determine the call holding time, which is included in the message.

If a command unit serves 100 lines, then a typical interrogation rate might be 10 lines per second, each responding at a data rate allowing each 30 bytes message structure to be sent in 50 ms.

Time information derivation may use separate scan counters at the telephone set units, rather than depending on synchronised individual clocks. Operation in this case involves resetting the scan count at the telephone set unit to zero in the intitial scan after the command unit is activated. The real time of switch on and switch off is noted for the command unit, so all other information derived from the associated devices is defined as a consequence of known multiples of a standard scan time from switch on, or an essentially similar arrangement depending upon the proviso program adopted for scanning in a particular instance.

Where, as is the case in the application of the system to a large PABX, there are several command units, each command unit has a discrete block of inerrogation signals to ensure that difficulties do not occur due to interpenetration of RF fields.

Claims (7)

1. Traffic measuring apparatus for monitoring call establishment at a defined point in a telecommunications system, which includes a sensor associated with but not in physical contact with the transmission medium at the defined point, which sensor responds to conditions at the defined point relevant to call establishments involving that defined point, storage means associated with the sensor in which information relative to said call establishments or attempts therefor responded to by the sensor are stored, and a radio transmitter associated with said storage means and adapted to transmit to a remote point, when required, measages each of which identifies the defined point and includes details of call establishments extracted from the storage means.

2. Apparatus as claimed in claim 1, and in which the transmitter is arranged to transmit said messages at preset intervals, or at preset times.

3. Apparatus as claimed in claim 1 or 2, and which includes a radio receiver which, in response to a request for information, causes a specific transmitter to send a message appropriate to the current contents of the storage means.

4. Apparatus as claimed in claim 2 and 3, and in which when a said message has been effectively received the storage means is cleared.

5. Apparatus as claimed in claim 1, 2, 3 or 4, and wherein the sensor is an inductive sensor adjacent to the transmission medium at the said defined point.

6. Apparatus as claimed in claim 1, 2, 3 4 or 5, and wherein the defined point is a telephone subscriber's terminal and the sensor responds to both incoming and outgoing communication connections.

7. Traffic measuring apparatus substantially as described with reference to the accompanying drawings.