Method for the insertion of audible tones in existing voice connections in a telephone exchange.

p0001The invention relates to a method for feeding audio tones into existing calls with a telephone exchange system according to the preamble of claim 1.

p0002From DE-OS 32 16 784 a circuit arrangement for supplying an audible tone to the speech of a digitally by switching to the time division principle telephone switching system is known. It involves a relatively simple circuit arrangement, whereby a pulse is formed by counter and links from a control clock, corresponding to the repetition period of the fundamental frequency of the audible tone. This pulse is not tagged with a connection information and a rhythm clock and passed through a transmission gate to a busbar. This is sent instead of a language sample word zero potential. As this process is repeated in a regular sequence, creates a audible tone at the predetermined fundamental frequency. In such Hörtoneinspeisung it is not possible to send an audible tone targeted to only one subscriber, the other party does not hear this audible tone. Furthermore, a generated in this way and coupled-audible tone in its quality can not be compared with an audible tone, has a sinusoidal fundamental frequency.

p0003A circuit arrangement for switching in time division multiplex telecommunication switching systems is known from DE-PS 20 41 604th This is a hybrid amplifier arrangement for a for a pulse amplitude modulation principle (PAM) by-switching telecommunications switching system. Here two participants are added analogously in each mixer amplifier and a third participant received as amplitude sample respectively by integrating obtained from analog samples speech components. In this way, a three-way conference connection is established, as occurs, for example, if it is made in a telephone private branch exchange from the operator or attendant of an intrusion into an existing call.

p0004From DE-AS 18 03 222, a method for combining pulse-coded message is known. It also is preparing a three-way conference connection, whereby instead of an analog additon the digitized speech samples of two words participants added together and will be sent to a third party. To perform an addition, the codewords previously must be linearized, when compressed, for example, according to a logarithmic curve. When made in this way gekommenene three-party conference call, participants involved are as previously described so interconnected that each can speak and can hear the other two parties. It is not readily possible with these simple requirements, in addition audible tones can be coupled and / or that these audible tones can be a member only offered selectively.

p0005The object of the invention is to use without additional effort an existing for the production of three-way conference compounds mixing means for feeding audio tones so that an audible tone targeted only one subscriber can also be sent. A variety of different audio tones is intended to be switched through the smallest possible number of connection timings.

p0006This object is achieved with a combination of features as set forth in claim. 1

p0007This is achieved in an advantageous manner that occurring in a telephone exchange dial tones when required can be only one participant, offered with no extra effort also targeted. Here are the ways to make conference calls, only slightly restricted. Advantageous developments of the invention result from the dependent claims.

p0008An embodiment of the invention is explained in detail with reference to drawings. It shows:<ul><li>FIG. 1 shows the block diagram of a telephone switching system.</li><li>FIG. 2 shows the circuit diagram of a mixer device.</li><li>Fig. 3 is a timing diagram for various call progress tones.</li></ul>

p0009In Fig. 1 is a block diagram of a telephone switching system is shown, which connects through digital time division multiplexing principle. The information to be exchanged primarily speech samples are transmitted while encoded by the known PCM principle. The connecting elements AO1.1 to AOm.n are groups connected to a coupling network CN RZ, which is designed according to the space-time multi-principle. For each connection member groups AO1 to AOM lead digitally operated busbars SS1 to Sm. On each of these busbars the connected terminal organs AO are a verbestimmte number of time slots available.

p0010For most telephone exchanges are the connecting elements AO with subscriber terminals, so wired with telephone sets. However, the terminal organs AO can be wired with connecting cables, which lead to other telephone exchanges.

p0011For the coupling of call progress tones, but also for making conference calls mixer means ME is connected via a mixer busbar M-SS to the coupling network CN RZ. This mixer busbar M-SS of the mixer means ME are a predetermined number of time slots mixer ZLM available. These mixers timings ZLM, for example 32, are divided into time slots for conference calls ZLK and time slots for call progress tones ZL1 to ISN.

p0012In addition, a Hörtongenerator HTG a Hörtonsammelschiene HT-SS is connected to the switching network CN RZ. The Hörtongenerator HTG provides thereby the governing Hörtonfrequenzen digital words that are stored there after the pulse-code modulation PCM principle.

p0013For the award of time slots within the coupling network CN RZ and for switching through the existing there spatial connection paths a control device SE is responsible. On the features of this controller will be discussed hereinafter only in so far as it is necessary for an understanding of the functions related to the invention.

p0014Fig. 2 shows a block diagram of the mixer device ME itself. The connecting relationships lying in different time slots of ZL1, ZL2 and ZL3 are shown spatially separated in FIG. 2. About a Mischkoppler MK two incoming signal directions are summarized by two PCM words are added after linearization. The newly created thereby linearized sum word is compressed in a known manner and passes each to the sending direction of the third link.

p0015A practical example will now be described as an audible tone to one of two connected participants will be sent. Assume here that a call connection between the devices connected to the terminal organs AO1.1 and AO1.3 subscribers A and C is. any time slot ZL is for this call connection then at the busbar SS1 is what both call directions are switched through the time division principle accordingly.

p0016Now, if for example, the subscriber C is to receive an audible tone, it is made in accordance with the connection state by the control device SE. For the time period in which each of the audible tone HT is to be sent, the previous reception time position of the station C is shut down within each of the coupling network. Instead, available for Hörtoneinspeisung the mixer device ME timing, eg ZL3 him is provided. By switching off the reception timing of the audio sound HT receiving subscriber C, the transmission timing of his interlocutor, the subscriber A is turned off simultaneously. This gets instead a time slot, provided in Example ZL1 available, which is the mixer device ME assigned. As can be seen from Fig. 2, data sent by the subscriber A speech samples words in the time slot 1 is received via a call leg VA in the mixer device ME. At another time position in the example ZL2 receives the mixer device ME through the mixer busbar MSS informed of the call leg VB the audible tone HT. The received from subscriber A via the call leg VA speech samples words are mixed with the digitized samples of the audible tone HT, that is added, and the subscriber C sent in the third time slot ZL3. When participants C then the originating from the interlocutor A voice information is superimposed on the audible tone HT. This connecting state is shown in Fig. 2 within the mixer coupler MK by solid lines.

p0017In the event that in certain connection states an audible tone HT is to be fed, which is to arrive at the two subscribers A and C, so a timing switching is also made for the other call direction. then the timing ZL1 and the timing ZL3 is allocated for the duration of the emission of the audible tone HT on the other call direction. In Mischerkoppler MK then the incoming from the subscriber C via the connecting leg VC voice signal is mixed with the on call leg VB incoming Hörton- PCM words, so that the other party A can receive the audible tone HT. This connection relationships are illustrated by dashed lines in Fig. 2 within the mixer coupler MK.

p0018Another output of the mixer coupler MK which is indicated in the drawing A + C, is not required when the Hörtoneinkopplung. He is therefore in each time slot, in the example ZL2 inactive in the audible tone HT arrives from Hörtongenerator HTG. If as described above, the audio sound HT is coupled only in a conversation direction, so is not active at one or the other receiving direction VA or VC within the mixer device ME. In this case, the respective time slots to mixer means ME are switched from Hörtongenerator from, said Hörtongenerator HTG sends PCM words representing a zero level. This is to avoid that occur on the busbars unwanted sound effects.

p0019Since for each coupling a specific audible tone HT a three time slots timing group, for example ZL1 to ZL3 must be available, the traffic capacity of a telephone switching system will be severely limited if very many time slots for coupling a plurality were lost by various audible tones. Therefore, the invention also foresees that various Hörtonphasen be set P1 to P5, as shown in Fig. 3. The classification of these phases P depends, of course, how great is the distance between two tones at a very specific audible tone as HT1. If so, as shown in Fig. 3, the sound each takes one second and the distance is four seconds, up to five phases can be formed. The individual progress tones, then can in this case HT1 to HT 5 on the same time slot group, are sent in the example ZL1 to ZL3 and each have a different meaning. So it can be for example when an audible tone HT1 be a call-waiting tone that signals the operator concerned that another connection is waiting for him. Another audible tone HT2 could be the meaning assigned to that there is an alert tone, the signals that are present at a night-connected subscriber station further incoming calls. In another audible tone HT3 it could be a cut-in tone. To make the different meanings of such audible tones HT participants clear to the individual audible tones distinguish the example HT1 to HT 5 in that they have different frequencies. However, the Tonsendung may also be interrupted, as shown for one of the call progress tones HT5.

p0020Since a timing switching is performed only during an existing call connection, if indeed an audible tone HT should be sent, and the call each during breaks, in the example, four seconds to return each to its original state, the same time slots, in the example ZL1 to ZL3 the mixer device ME can be used during this interim period for other compounds. In this case, SE is a timing switch such made in the connection of the Hörtongenerators HTG with the mixer device ME, that, if necessary, another audible tone, for example, HT2 is connected across the said mixer means ME assigned timing, in the example ZL2 to mixer device ME by the control means. The control device SE so on each phase P1 to P5 according to one of the audible tones HT1 to HT 5 to mixer means.

p0021So if the mixer device ME three timing groups, eg be ZL1 to ZL3, made of three time slots, for a total of nine time slots available, so can the example described according to a total of fifteen different Hörtonarten in the switching network CN RZ switch if a time interleaving , as shown in Fig. 3, is possible.