GB2082421A - Telephone exchanges - Google Patents

Abstract

In an office system the control unit has a "ringing" list which is used to determine the most likely recipient of an incoming call. The telephone which has previously cleared the most incoming calls is called first and longest. In the absence of a reply the next telephone in the list is called for a shorter period in dependance upon the difference between the number of incoming calls cleared by each of the telephones and so on down the ringing list. Limits are applied to the difference between the number of incoming calls cleared by each telephone, as stored in the list, so that incoming calls are not left unanswered for excessive time periods in the absence of a reply from the more popular telephones.

Description

SPECIFICATION Telephone exchanges The present invention relates to telephone exchanges and in particular to such systems of the kind known as private branch exchanges.

There is a tendence not to provide operator positions per se in small telephone exchanges intended for installation in offices for example.

Consequently when an incoming call is received by such an exchange either all or some of the telephones connected thereto must be called by the exchange and the call connected to the telephone which is answered first. The user of the answered telephone must now ascertain from the caller to which telephone the call should be connected and then transfer the call accordingly.

It is an object of the present invention to provide a telephone system in which an incoming call is connected to a telephone which is most likely to be the telephone to which connection is required.

According to the present invention in a telephone exchange having a switching network arranged for connecting calls between or to a plurality of telephones, and a line on which incoming calls are received for connection to the telephones by way of the switching network, control means which is for setting up calls through the switching network and which comprises a store arranged to store respective data relating to the number of incoming calls cleared by each of the plurality of telephones, means to compare the data stored in respect of each of the plurality of telephones each time an incoming call is received to determine which telephone has previously cleared the most incoming calls, and means to modify the data stored in respect of each telephone each time the respective telephone clears a call, the control means being arranged to provide ring current by way of the switching network to the telephone which has previously cleared the most incoming calls as determined by the comparison means in respect of each incoming call.

Preferably if the called telephone is not answered within a predetermined period or is engaged the control means is arranged to provide ringing current by way of the switching network to the telephone which has cleared the next most incoming calls.

If the next called telephone is not answered within a second predetermined period or is engaged the control means may be arranged to activate the respective calling device of each telephone in turn for a respective predetermined period.

The second predetermined period may be shorter than the first predetermined period and the third and each subsequent predetermined period may be shorter than its respective previous predetermined period.

The predetermined period during which each calling device is activated may be dependant upon the difference between the number of incoming calls cleared by the telephone which has released the incoming line the most times and the number of incoming calls cleared by the telephone to which ringing current is being provided with the control means being arranged to provide ringing current to each telephone for a minimum period of time.

Modification of the data associated with the telephone which has cleared the most incoming calls may be inhibited if the difference between the number of incoming calls cleared by said telephone and the number of incoming calls cleared by any of the other telephones exceeds a predetermined numerical limit.

A telephone system including a telephone exchange in accordance with the present invention will now be described with reference to the accompanying drawings of which Fig.

1 shows the system in a simplified block diagram form, and Fig. 2 shows a data table associated with the exchange of Fig. 1.

Referring to the drawings the system comprises a switching network 2 to which are connected a number of telephones 3 to 8.

Calls between the telephones 3 to 8 are set up through the switching network 2 under the control of a central control unit 1 which is also arranged to set up calls between incoming exchange lines 9 and 10 and the telephones 3 to 8.

The control unit 1 may be a microprocessor together with a programmable read-only-memory (PROM) for programme storage and a random access memory (RAM) for data storage, a part of which is shown in a data table form 11 in Fig. 2.

Facilities offered by the system include direct connection of any one of the telephones 3 to 8 to one of the exchange lines 9 and 10 for direct dialling out of calls. The exchange lines 9 and 10 are not necessarily connected to the same exchange, one of them possibly being connected for example to a public telephone exchange and the other being connected to a private automatic exchange either local to or distant from the system.

Each of the telephones 3 to 8 has an exchange recall button (for example of the earth return kind arranged to cause line imbalance) and means to signal digits, for example a dial or keypad, to the central control unit 1.

The system may be of the kind described in greater detail in our co-pending Patent Applications Nos. 8014274 and 8124117.

For accounting purposes the central control unit 1 deems the one of the telephones 3 to 8 which clears a call received from one of the incoming lines 9 and 10 to be the telephone for which the incoming call was intended regardless of the number of times that call has been transferred between the telephones 3 to 8.

The invention is primarily concerned with the way in which the central control unit 1 handles calls incoming from the incoming lines 9 and 10. The switching and transfer of calls between the telephones 3 to 8 is handled in known manner and is not discussed further herein.

When an incoming call is detected by the central control unit 1 by means of (for example), a ringing detector (not shown) on one of the exchange lines, say, 9 the control unit 1 examines the upper half of the data table 11 in which is accumulated the number of calls received from the incoming line 9 which have been cleared by each of the telephones 3 to 8. As shown in the table 11 the telephone 5 would have cleared 22 calls received on line 9, the telephone 7 having cleared 14 and so on.

The central control unit 1 proceeds on the basis that the telephone 5 has cleared most of the calls received on the line 9 and therefore is the most likely telephone to receive the present incoming call. Thus, if the telephone 5 is not in use, the central control unit 1 causes the line 9 to be connected through the switching network 2 to the telephone 5 and that telephone's calling device will operate to the ringing current on the line 9.

Assuming that the telephone 5 is answered, within a period of time determined as hereinafter described, the central control unit 1 monitors the call and if it is not transferred to one of the other telephones 3, 4 or 6 to 8, when the call is cleared, increments the calls record for the telephone 5.

If the incoming call is not for the user of the telephone 5, the user will determine from the caller which telephone is required and will operate his transfer button and dial the number of the required telephone, say, 4. The central control unit 1 therefore deems the call to be a call to the telephone 4 and when the call clears, increments the calls record for the telephone 4. Since the telephone 4 is not the telephone which has received the most calls from the incoming line 10 the central control unit 1 now compares the number of calls received by the telephone 4 with the number of calls received by the next telephone above the telephone 4 is the list that is the telephone 3.

If after clearing the call the telephone 4 is found to have received more calls than the telephone 3 the control unit 1 re-arranges the list so that the telephone 4 and its calls record is above the telephone 3 in the list and compares its calls record with the next telephone in the list.

This process continues until the list is again in the correct order.

If the telephone 5 is in use when an incoming call is received on the line 9, then the central control unit 1 will cause the switching network 2 to connect the call to the next telephone in the list, that is the telephone 7 unless that is also engaged in which case the call is connected to the first telephone in the list which the central control unit 1 determines to be free.

If all lines are engaged the central control 1 may be arranged to introduce an intrusion tone (for example a "tick" tone) to either the first telephone in the list or the last telephone in the list or to all the telephones or any combination of telephones and will cause the switching network 2 to connect the call to the first of the telephones to become free.

Constraints may be applied to the central control unit 1 such that the intrusion tone is' not introduced to a telephone which is already engaged on a call to one of the other exchange lines for example.

In order that a caller on the incoming line is not kept waiting for long periods of time the central control unit 1 is arranged to offer the call to each of the telephones 3 to 8 in the order in which they appear in the list until one of the telephones is answered.

One method is to use a fixed predetermined period (for example of sufficient time to allow say eight rings of a telephone bell) such that if the telephone 5 is not answered within the predetermined period the calling device of the telephone 7 is operated for a similar period and so on through the list until an answer is received.

A preferred method is to allow the first telephone, the telephone 5 a longer period than the next telephone, the telephone 7 and to allow each subsequent telephone a shorter period than its predecessor subject to each of the telephones receiving a minimum calling time. For example the telephone 5 may receive eight "rings", the telephone 7 six "rings", the telephone 3 four "rings" and each of the remaining telephones two "rings".

If none of the telephones 3 to 8 is answered after a first pass through the list the central control unit 1 may be arranged to repeat the procedure until one of the telephones is answered or may be arranged to call all of the telephones, or any predetermined ones, and to connect the call to the first telephone to be answered.

It will be appreciated that the calling period may be determined from the number of calls previously cleared such that if, for example the telephone 5 had previously cleared 22 calls and the telephone 7 twenty-one calls each would receive eight "rings" the subsequent telephones receiving respectively six, four and two "rings".

Incoming calls on the line 10 are handled in a similar manner to those received on the line 9 but with reference to the lower half of the table 11.

It will be appreciated that a combination of calls cleared on each of the lines may be used to determine the order in which the telephones 3 to 8 are called. It will also be realised that all of the telephones 3 to 8 need not appear in each list. In circumstances where, say, the telephone 3 is not included in the line 9 list although incoming calls on the line 9 may be transferred to the telephone 3 by one of the other telephones the central control unit 1 will ignore such calls for accounting purposes.

A further facility which may be easily provided is to credit calls cleared by one of the telephones to another of the telephones such that if say the telephone 7 is used by an office manager and the telephone 5 by the office manager's secretary, calls cleared by the telephone 7 may be credited in the list to the telephone 5 or to both of the telephones 5 and 7.

Limits may be applied to the difference between the calls cleared credited to any two telephones. A practical limit is eight so that if the first telephone is, say, telephone 5 having cleared 22 incoming calls from the line 9 and the second telephone 7 has cleared 14 calls from the line 9 the call credit of telephone 5 will not be incremented further until the telephone 7 has cleared a further call. This ensures that if the normal user of the telephone 5 is not handling calls for any reason, such as being away on holiday for example, the telephone 7 will fairly rapidly become the most likely telephone to require the call connection.

In the case of the second and subsequent telephone in the list the difference may be limited to eight by also incrementing the call credit of the subsequent telephone or telephones in the list if incrementing the respective figure for the telephone which has cleared the current call will cause the limit to be exceeded.

It will also be realised that if the call count is consistently incremented over a period of time the call count will reach the limit of the store. Therefore periodically say on a daily basis either the call count for each telephone must be completely cleared or amended in some way such as clearing the last telephones call count and setting the respective call count for each telephone above the last telephone is the table 11 to, say, one higher than its predecessor in the list.

An alternative method of implementing the invention which prevents the call count reaching the limit of the storage will now be described.

The data table 11 for each incoming line 9 and 10 is limited to four of the telephones 3 to 8 with the call count previously described being used as a "ring" count. If the table 11 for the incoming line 9 for example has the four telephones 5, 7, 3 and 4 in its list in that order, then, when a further incoming call is received the telephone 5 will be called for a period of time dependant upon the "ring" count. If the telephone 5 is not answered then the telephone 7 is called for a shorter or similar period of time in dependance upon its respective "ring" count and similarly, if the telephone 7 is not answered, the telephone 3 is called for a similar or shorter period in accordance with its respective "ring" count. If the telephone 3 is not answered then the telephone 4 is called for a fixed minimum period which is equivalent to two ringing periods of the telephone bell.If none of the four telephones in the list is answered then the procedure may be repeated.

When a call is cleared the telephone which cleared that call is deemed to be the telephone for which the call was intended. If the telephone which clears the call, say the telephone 8, is not already in the "ring list" the fourth telephone 4 will be replaced in the list by the telephone 8.

As each telephone in the list clears subsequent calls if it is one of the first three telephones in the list the respective "ring count" will be incremented, unless incrementing the "ring count" would cause the "ring count" to exceed the "ring count" of the next lower telephone in the list by six. Should the limit be reached if the telephone clearing a call is the second or third telephone in the list then the "ring count" of all telephones in the list above the present telephone is decremented.

Whenever the fourth telephone in the list clears a call the respective "ring count" of all the other telephones in the list is decremented.

On completion of the adjustment of the respective "ring counts", if the telephone clearing a call is not at the top of the list the central control unit 1 compares the "ring count" of the telephone which has cleared the call with the "ring count" of the telephone next highest in the list. If the respective "ring counts" are equal the two telephones change places in the list and the "ring count" of the telephone which has cleared the call is compared with that of the next highest telephone in the list.

Thus any of the telephones 3 to 8 may enter any of the lists 11 for any one or more of the lines 9 and 10 and may climb the list quite rapidly if a series of calls on a particular line are for that particular telephone.

The system may have provision for calls to any particular telephone to be automatically diverted to another telephone. When this invention is invoked ringing will be diverted accordingly but the calls record will be updated as before. An example of this is as follows: A Manager may have calls diverted to a secretary who may then transfer them to the manager's telephone. When he clears down such a transferred call his call record is updated in the call list. If the secretary clears a diverted call the call record of the manager's telephone will be updated in the call list but if the call was intended for the secretary (i.e. not diverted) the call record of the secretary's telephone will be updated. Subsequently removal of divert leaves the calls record list correct.

Claims (10)

1. In a telephone exchange having a switching network arranged for connecting calls between or to a plurality of telephones, and a line on which incoming calls are received for connection to the telephones by way of the switching network, control means which is for setting up the calls through tl e switching network and which comprises a store arranged to store respective data relating to the number of incoming calls cleared by each of the plurality of telephones, means to compare the data stored in respect of each of the plurality of telephones each time an incoming call is received to determine which telephone has previously cleared the most incoming calls, and means to modify the data stored in respect of each telephone each time the respective telephone clears a call, the control means being arranged to provide ring current by way of the switching network to the telephone which has previously cleared the most incoming calls as determined by the comparison means in respect of each incoming call.

2. Control means as claimed in Claim 1 also arranged, if the telephone which has previously cleared the most incoming calls is engaged, to provide ringing current by way of the switching network to the telephone which has cleared the next most incoming calls.

3. Control means as claimed in Claim 1 or Claim 2 also arranged, if the telephone to which ringing current is provided is not answered within a first predetermined period, to provide ringing current to the telephone which has cleared the next most incoming calls.

4. Control means as claimed in Claim 3 further arranged, if the next telephone to which ringing current is provided is not answered within a second predetermined period, to provide ringing current to the telephone which has cleared the next most incoming calls.

5. Control means as claimed in Claim 4 in which the first predetermined period is substantially of the same duration as the second predetermined period.

6. Control means as claimed in Claim 4 in which the first predetermined period is of longer duration than the second predetermined period.

7. Control means as claimed in any preceding claim in which the data stored in respect of the respective number of calls cleared by each of the telephones characterises a list arranged in descending order with the telephone which has cleared the most incoming calls first and the telephone which has cleared the least incoming calls last, and the control means is arranged to provide ringing current by way of the switching network to each telephone in the list in turn for a respective predetermined period until one of the telephones is answered.

8. Control means as claimed in Claim 6 or Claim 7 in which the difference between the duration of the respective predetermined periods is determined by the difference between the number of calls cleared by the respective telephone to which ringing current is being provided and the number of calls cleared by the telephone to which ringing current was last provided.

9. Control means as claimed in Claim 8 arranged to inhibit the modification of data held in respect of the number of calls cleared by any one of the plurality of telephones if the difference between the respective number of incoming calls cleared by telephone and the respective number of incoming calls cleared by the telephone which has cleared the next most incoming calls would exceed a predetermined number.

10. Control means substantially as hereinbefore described with reference to the accompanying drawing.