PROCEDURE AND SYSTEM FOR INDICATING A CALL IN HOLD STATE IN A TELECOMMUNICATION SYSTEM

Abstract: The present invention concerns a method and system for indicating a call in hold state. In the invention, a message containing information regarding a call in hold state is sent from a local exchange to a telecommunication terminal. The information contained in the message is converted in the telecommunication terminal into a string to be presented on the display or into sound signals. The invention makes it possible to prevent calls in hold state from being left "hanging".

Description: PROCEDURE AND SYSTEM FOR INDICATING A CALL IN HOLD STATE IN A TELECOMMUNICATION SYSTEM The present invention relates to a method as defined in the preamble of claim 1 and a system as de- fined in the preamble of claim 7 for indicating a call in hold state on a terminal in a telecommunication network. ISDN is a digital transmission system in a digital telephone network. Using the ISDN system, voice and data services are implemented for subscribers connected to the telephone network. There are two types of access defined in the ISDN system: base access (BA) and primary rate access (PRA) . Using a base access, it is possible to connect to the public tele- 5 phone network a single telecommunication terminal or a set of max. eight terminals, in which case at most two B channels terminals may be active at the same time. It is also possible to connect a so-called integrated services digital private branch exchange (ISPBX) to a 0 base access or base accesses. The standards define various basic services, such as call transfer, setting a call into hold state, enquiry call, call waiting etc., which the subscriber can activate for use by making a specific selection on 5 his/her terminal or by having them switched in the exchange by the operator. When an ISDN subscriber sets a call into hold state, the connection with the called subscriber is not broken off but held open until the calling subscriber resumes the call being held. If the 0 user does not resume the call, it may remain in hold state for a long time. At present, there is no timeout or corresponding procedure defined in the telephone exchange to resume a call in hold state. On the other hand, there are terminals which can store infor- 5 mation regarding calls in hold state, so they do not need any reminder from the exchange. However, there are also terminals and applications that have no such property. For instance, applications implemented on computer via the CAPI/PCI interface do not necessarily have their own timers, and hold- state time-outs are impracticable or impossible to implement. In general, it can be stated that there are many applications m which hold-state time-outs are needed. In addition, it is possible that the calling and called subscribers set the same call into hold state. In this case, the connection between the subscribers will remain on for a very long time. The object of the present invention is to eliminate or at least to significantly reduce the drawbacks described above. A specific object of the present invention is to disclose a new property or feature which is easy to implement m existing telephone exchanges and which provides a usable additional feature m ISDN services. As for the features characteristic of the present invention, reference is made to the claims. In the method of the present invention for indicating a call m hold state in a telecommunication network, a first message is sent for setting a call into hold state, whereupon the local exchange sets the call into hold state in a certain manner. When the user of the terminal wishes to resume the call being held, a second message is sent from the terminal for resuming the call and connecting the terminal to the call being held. The first and second messages are defined m ETSI standard series I.100 - 1.400, which de- scribe ISDN services. The telecommunication network comprises a local exchange with an ISDN capability implemented m it. Moreover, connected to the local exchange is an ISDN terminal supporting ISDN functions. According to the invention, a third message, which contains information regarding the call m hold state, is sent from the local exchange to the terminal . The instant of transmission of the third message is preferably determined by a time-out which is started when the call is set into hold state. Based on the time-out, the third message is sent repeatedly at certain time intervals. The duration of the time in- tervals can be changed so that a reminder is sent the more frequently the longer the call remains in hold state. It is also possible to send a reminder at intervals whose duration is increased in proportion to the length of time the call remains in hold state. In addition, the invention can be combined with an arrangement whereby the number of information messages sent is monitored and when the number exceeds a predetermined limit, then the call in hold state is disconnected. This additional feature could be imple- mented separately for each subscriber so that the subscriber can him/herself set a limit for the number of information messages or similarly for the length of time for which a call may remain in hold state. In this way, e.g. in applications used in computers, a control function can be set so that a call in hold state will not remain "hanging" . After a call in hold state has been disconnected, a fourth message is sent from the local exchange to the terminal to inform the user that the call has been disconnected. When the terminal has received the third message, it can convert the information contained in the message into a string to be presented on the display of the terminal or into a sound signal to be output for the user via the handset. Other methods of indica- tion can also be used. In a preferred embodiment, a message acknowledging the first message is sent which contains information about the call to be set into hold state and/or about its being set into hold state. The acknowledge- ment message may contain the called party's subscriber number and the time at the instant the call was set into hold state. In addition, an acknowledgement mes- sage with corresponding content may be sent in response to the second message, in which case the acknowledgement message contains information about the call held and/or resumption of the call. As compared with prior art, the invention provides the advantage that the user of the terminal is informed periodically about the call in hold state. Thus, the user can either disconnect the call him/herself to avoid increasing the call costs or he/she may resume the call. Moreover, the invention makes it possible to prevent the occurrence of "hanging" calls. The system of the present invention for indicating a call in hold state in a telecommunication network comprises means for sending a first and a second message from a telecommunication terminal to a local exchange. The means for sending the messages are implemented in the telecommunication terminal and so connected to the user interface of the terminal that the user of the terminal can send said messages when he/she wishes to. According to the invention, the system comprises means for sending a third message from the local exchange to the telecommunication terminal, said third message containing information regarding the call in hold state. The system preferably also comprises means for implementing a time-out in the local exchange, allowing the intervals of transmission of third messages and the number of messages sent to be monitored. This allows the auxiliary function accomplished by the invention to be made more effective. In the following, the invention will be described by the aid of preferred embodiments with reference to the attached drawing, wherein Fig. 1 presents a preferred system according to the present invention; and Fig. 2 presents a signal diagram for a preferred embodiment of the present invention. The system presented in Fig. 1 comprises a local exchange LE and a telecommunication terminal TE . The terminal TE is connected to the local exchange LE via an ISDN base access (2b + d) . This type of access comprises two voice channels with a capacity of 64 kBit/s and a signalling channel D with a capacity of 16 kBit/s. The telecommunication terminal comprises means 1 for sending a first and a second message to the local exchange LE . These means are implemented using technology known in itself and are obvious to the skilled person, which is why they will not be de- scribed here in detail. The telephone exchange comprises means 2 for sending a third message. The third message is a notice sent to the ISDN terminal TE about a call in hold state. Moreover, the local exchange LE comprises means 3 for accomplishing a time-out. The implementation of means 2 and 3 is also obvious to the skilled person, so they will not be described here in detail . Next, referring to Fig. 2, a preferred example of the method of the invention will be presented. Fig. 2 presents the signalling between the telecommunication terminal TE and the local exchange LE in a case according to the present invention. At the beginning, the call is in active state. When the user of the terminal wants to set the call into hold state, he/she will give the terminal a command to send a first message. In this case, the first message is a HOLD message consistent with the ISDN specifications, which sets the call into hold state. The local exchange acknowledges the message by returning a 'call in hold state' message, which is a HOLD ACK message consistent with the ISDN specifications. In conjunction with this acknowledgement message, it is possible to send an information text: "Call set into hold state 12:23, number <12345> or user Peter P" . After the 'call in hold state' message, a time-out of predetermined duration is started. Upon tripping of the time- out, a third message is sent from the local exchange LE to the terminal TE . In this example, the information is sent using "display" information, which has been designed for the transmission of messages from the network to the users . After the third message, the time-out is immediately started again. If a feature whereby the duration and number of repetitions of the time-out are changed is in use, then before restarting the time-out a check is carried out to determine whether the dura- tion has to be changed or whether the notice is being sent for the last time. If the notice is being sent for the last time, then the call in hold state is disconnected and a corresponding message (not shown in Fig. 2) is sent to the terminal. When the user of the terminal receives the third message, converted into a "call in hold state" message on the display of the terminal TE, the user may resume the call being held. To do this, he/she gives the terminal TE an instruction to send a second message to the local exchange LE . In this case, the second message is a retrieve message consistent with the ISDN specifications. The local exchange acknowledges the message sent by the terminal by returning a 'retrieve ack ' ISDN message. In conjunction with this acknowledgement message, it is possible to send an information text: "Call resumed 12:28, number <12345>". After this, the time-out in the local exchange is stopped and the call is restored to the normal activate state. The invention is not restricted to the em- bodiment example described above, but many variations are possible within the scope of the inventive idea defined in the claims

Claims: CLAIMS 1. Method for indicating a call in hold state in a telecommunication network comprising a local exchange (LE) and a telecommunication terminal (TE) con- nected to the local exchange, in which method a first message is sent from the telecommunication terminal to the local exchange to set the call into hold state, and a second message is sent from the terminal to resume the call in hold state and connect the terminal to the call, charac t er i s e d in that a third message is sent from the local exchange to the telecommunication terminal, said third message containing information regarding the call in hold state. 2. Method as defined in claim 1, char - ac t e r i s ed in that a time-out is started when the call is set into hold state, and the third message is sent repeatedly at predetermined time intervals on the basis of the time-out. 3. Method as defined in claim 2, char - act er i s ed in that the duration of the time-out is changed. 4. Method as defined in any one of the preceding claims 1 - 3, charac t e r i s ed in that the number of information messages is monitored and when the number exceeds a predetermined limit, then the call in hold state is disconnected. 5. Method as defined in claim 4, char ac t er i s ed in that a fourth message is sent from the local exchange (LE) to the telecommunication ter- minal (TE) to inform the user about the disconnected call. 6. Method as defined in any one of the preceding claims 1 - 5, charac t e r i s e d in that the third message is converted into information pre- sented on the display of the telecommunication terminal and/or into a sound signal in the telecommunication terminal . 7. Method as defined in any one of the preceding claims 1 - 6, charac t e r i s ed in that the first message is answered by sending an acknowledgement message containing information about the call to be set into hold state and/or about its being set into hold state. 8. Method as defined in any one of the preceding claims 1 - 7, charact eri sed in that the second message is answered by sending an acknow- ledgement message containing information about the call in hold state and/or resumption of the call. 9. System for indicating a call in hold state in a telecommunication network comprising a local exchange (LE) and a telecommunication terminal (TE) con- nected to the local exchange, said telecommunication terminal comprising means (1) for sending a first message to set the call into hold state and a second message for resumption of the call, character i s e d in that the local exchange comprises means (2) for sending a third message, said third message containing information regarding the call in hold state. 10. System as defined in claim 9, char ac t eri sed in that the local exchange comprises means (3) for accomplishing a time-out for the call in hold state.

Inventors: PERNU SAKARI, PERNU, SAKARI
Applicants: NOKIA TELECOMMUNICATIONS OY, PERNU SAKARI, PERNU, SAKARI
Application year: 1999
Main classification: H04Q7
IPC codes: H04M3, H04Q11