DE102005046170A1 - DTMF dialing signals insertion method e.g. into data stream containing data packets, involves inserting DTMF dialing signals into data packets of data stream in which coded useful information is contained - Google Patents

Abstract

The method involves inserting DTMF dialing signals (DSD8) into data packets (A1, A2, A3,...) of a data stream in which coded useful information is contained. The possible DTMF signals are digitized and coded and stored as packets in place of the useful information contained within packets and inserted into the data stream in such a way that packets rejected provided and packets with useful information are modified. An independent claim is included for a device.

Description

method to paste of DTMF dialing signals in a data packet comprising data stream in which encoded User information is included.

The abbreviation DTMF stands for Dual Time Multi-Frequency Method. In German it is also called DTMF (DTMF). DTMF is today in the telephone switching technology for transmission from telephone numbers to a telecommunications network or to a private branch exchange and as a remote control option for value-added services, Answering machine or other remote diagnosis devices used.

at DTMF are the digits of a telephone keypad of a push-button telephone as a so-called DTMF dial signal shown. A DTMF dial signal is generated by a mixture of two sinusoidal sound signals, which derived from the position of the key of a telecommunication terminal and be recognized in a telecommunication network.

row and columns of the keyboard of the telecommunication terminal at DTMF frequencies are assigned such that every line of the keyboard through a certain low frequency and every column of the keyboard represented by a certain high frequency. Becomes a specific one Button on the telephone keypad pressed, this is the DTMF dialing signal through overlays the low frequency of the key line with the high frequency of the key column generated. This DTMF dialing signal will then for the representation of the numbers 0-9 and the "#" and "*" keys used in telecommunication networks.

at Telecommunication networks can be used between circuit-switched telecommunications networks (e.g., Public Switched Telephone Network PSTN, Integrated Services Digital Network ISDN, Global System for Mobile Communications GSM, etc.) and packet-oriented telecommunications networks, also known as computer networks be distinguished.

at the circuit-switched telecommunications networks is a communication link temporarily a switched transmission channel with constant Bandwidth assigned to this connection then the exclusive Usage provided becomes. DTMF is in circuit-switched telecommunications networks as so-called in-band signaling method executed. This means the DTMF dialing signals are within the normal speech frequency band, ie within the so-called user data, and therefore can also be overheard.

At the packet-oriented telecommunications networks becomes a communication link no permanent, continuous, physical channel provided, but a data stream in small, single and sometimes different split long data packets, with additional information in these data packets such as. Identification of the data sources, identification of the target, Sequence number, etc. are packed.

For the controller the data transmission within a packet-oriented telecommunications network Protocols used. Used in a packet-oriented telecommunications network As the basic protocol using the Internet Protocol IP, these become Telecommunication networks are also often called IP-based telecommunications networks designated. The best-known IP-based telecommunications network is e.g. the Internet, like all the interconnected and the Internet Protocol IP using telecommunications networks is called.

meanwhile become IP-based telecommunications networks and thus the Internet Protocol also for the transfer from language - for the like called IP telephony or voice-over-IP - used. In IP telephony Although the language is initially analogous to a microphone (e.g. a telephone receiver). Then, however, the speech recorded by microphone becomes digital edited and then encoded or compressed to reduce the amount of data to be transmitted. The transport of the thus converted voice data, also called payload can be designated will then over performed an IP-based telecommunications network, wherein the voice data conditioned by that for the transport control competent Internet Protocol IP can be divided into many small data packets.

For the coding or compression of the data are used so-called codecs, which the digitally processed voice data in an audio binary format convert. Currently being for the data compression of voice data in Voice over IP, for example codecs according to the ITU-T standards G.711a, G.711u, G.722, G.723.1, G.726, G.728, G.729, etc. used.

Of the actual transport of the previously coded voice data is, for example, via the so-called real-time transport protocol RTP performed which preferred for Real-time applications such as for continuous transmission audiovisual data streams over IP-based Telecommunication networks is used.

Therefore, the RTP protocol is currently also in IP telephony signaling technologies such as Session Initiation Protocol SIP or H.323 - a higher-level ITU-T recommendation for audio-visual communication in packet-switched telecommunications networks based on other ITU-T protocols such as H .225, H.245, H.450, H.235, etc. - used to transmit the audio or video data streams of the communication link, that is, the payload or voice data between subscribers over the IP-based telecommunications network. This means that the data is encoded, packaged and sent using the RTP protocol. A data packet of the RTP protocol comprises a header, in which the version and sequence numbers for the receiver-side sorting of the data packets, data format, identification of the transmitter and time stamp are stored, as well as a user data part.

Around For example, communication links between circuit-switched Telecommunication networks and packet-oriented or IP-based telecommunications networks be able to produce Connection computer - so called gateways - used. Through these gateways, e.g. the circuit-switching B-channels an ISDN network terminates and from the information transmitted therein RTP user data stream for an IP-based telecommunications network are generated. The whole Gateway function, through which this interconnection different Types of telecommunication networks, includes the gateway, a gateway controller and a signaling gateway, also known as a softswitch becomes.

Of the Softswitch is thus a component of the IP-based telecommunications network, which plays an important role in IP telephony. From softswitch namely, will the control of gateways and the necessary signaling for IP telephony taken over. The signaling data for e.g. Setup and dismantling of communication are doing - similar to in modern circuit-switched telecommunications network technologies (e.g., ISDN, GSM) - disconnected from the data of the voice communication via own signaling protocols such as the ITU-T standard H.323 or SIP. This type of transfer signaling data is also referred to as out-of-band or out-band signaling designated.

in the Contrary to the circuit-switching telecommunication networks but in the IP-based telecommunications network of some components such as. some softswitches for Voice over IP or from PBXs for IP telephony also the DTMF dialing signal transferred outband. This means the information about the DTMF dialing signals will not - like common in circuit-switched telecommunications networks - together with the data of the voice communication, but over the own signaling protocol forwarded in the IP-based telecommunications network.

Gives It is now in an IP-based telecommunications network components such as. Gateways, of which an in-band signaling of the DTMF dialing signals provided or out of which no outband signaling the DTMF dialing signals supports will, so must information about an outband-signaled DTMF dialing signal be inserted in the data stream of the payload.

Around to solve this problem, Currently, so-called Digital Signal Processors DSPs are used, which are highly specialized but standardized and mass-produced Components for continuous and extremely fast, compute-intensive Processing a limited amount of input signals, e.g. outband-transmitted DTMF dialing signals are. However, the use of DSPs has proven disadvantageous that for the conversion of the DTMF dialing signals From outband to in-band signals with the DSPs a special hardware must be installed and administered, which makes this approach complex and also expensive.

Therefore The present invention is based on the object, a method and to provide a device by which packet-oriented telecommunications networks Outband-signaling DTMF dialing signals be converted without the use of special hardware, so that the DTMF dialing signals can be signaled inband.

According to the invention the solution this object by a method for inserting DTMF dialing signals in a data packet comprising data stream in which encoded Payload are included, with the possible DTMF dialing signals in digitized and encoded form, acting as data packets Place the payload information containing data packets in the Data stream inserted be that while of the feed process discarded data packets with payload then a number of the inserted data packets of the DTMF dialing signal is determined and after the feed-in the identifier of the data packets is modified with payload in a suitable form.

The main aspect of the method according to the invention is that the DTMF dialing signals are inserted into the data stream containing the payload, without the need for special hardware such as DSPs. In addition, by the Modification of the identification of the data packets with payload prevents unwanted effects on the receiver side, such as, for example, discarding the data packets with the information on the DTMF dialing signals.

It is advantageous if for the transfer of the Payload comprehensive data stream as a protocol the real-time transport protocol RTP is used as the RTP protocol a protocol standardized by the Internet Engineering Task Force IETF represents which for the transfer of real-time applications such as the voice telephony over IP suitable is. The RTP protocol will also work a so-called Forward Error Control is used, which by a extended header of the data packets is made possible. Through this extension of the Header is additional information such. the type of transferred Data (e.g., voice, video, etc.) or the time of creation the data stored in the data packet, making the data at the receiver easier put in a certain order or after expiration of a certain order Time can be discarded.

proposed will also, that as identifier of the data packets in the data stream a sequence number - a so called sequence number - or a Timestamp is used. By using the sequence number, in the RTP protocol, for example, in the header of the data packets can be deposited on the receiver side in a simple way the order of the transferred Data packets are restored. By adapting the sequence number, after the data packets of the DTMF dialing signal have been inserted can be transferred, the outband DTMF dialing signal be easily inserted into the data stream without changing the order the data packets disturbed becomes. On the receiver side can so despite the insertion of the DTMF dialing signal put the data packets back in the correct order in the data stream become.

The solution The task is further carried out by a device of the beginning mentioned Kind, means of insertion of possible DTMF dialing signals in digitized and coded form as data packets in the data stream in place of data packets with payload, means for determining the number of inserted Data packets of a DTMF dialing signal, and means for modifying the identifier of the data packets with payload are provided in a suitable form after the feeding process.

The achieved with the device according to the invention Advantages are in particular that for this device no special hardware such as. DSPs must be provided. In addition, the device according to the invention in a simple way between a network component with DTMF outband signaling and insert a network component with DTMF in-band signaling.

A special design variant the device according to the invention is characterized by the fact that means for depositing the possible DTMF dialing signals provided as samples in digitized and encoded form are, since the arrival of an outband signaled DTMF dial signal this be inserted quickly as a data stream comprising data packets can. Furthermore, there is the possibility the digitized and encoded DTMF dialing signals, for example in Form of files for to deposit the various codecs used so that the DTMF dialing signals are encoded in the same way as the data packets of the user data stream. information about the for the coding of the payload data codec can be used e.g. from the Signaling or from the incoming user data itself be determined.

The Invention will now be described by way of example with reference to FIG on the attached figures explained in more detail. It demonstrate:

1 the exemplary sequence of the inventive method for inserting DTMF dialing signals into a data packet comprising data stream with the aid of the device according to the invention

2 in an exemplary manner, the further transmission of the data stream after a DTMF dialing signal has been inserted by the device according to the invention

In 1 is the inventive device, which can also be referred to as a conversion server KS, shown, which is imposed on the first page S1, for example, to a softswitch or private branch exchange for IP telephony, out of which DTMF dialing outband - ie separated from one from data packets A1 , A2, ... existing user data stream - are sent. On the second side S2, the conversion server KS is connected to a network component that is not supported by outband signaling of DTMF dialing signals and to which the data stream is forwarded by the conversion server KS.

The DTMF dialing signals are stored in digitized and coded form on the conversion server KS, wherein the DTMF dialing signals in the conversion server KS can be digitized and coded for various possible codecs, for example in the form of files. In 1 is the one For the sake of simplicity, only one digitized and coded DTMF dial signal DSD8 is shown for eg the digit 8, this DTMF dial signal DSD8 for the digit 8 comprising for example 120 data packets D1, D2,..., D120. These data packets D1, D2,..., D120 of the DTMF dialing signal DSD8 were generated, for example, by sampling and by coding with the codec according to ITU-T standard G.723 for, for example, the RTP protocol as a transport protocol.

Now comes in a first step 11 on the first page S1 in the course of signaling an outband message DS8, in the information about a dial digit, for example, the number 8 is included, to the conversion server KS, the transmission of the outband message DS8 is active in an in-band DTMF dial signal. In a second step 12 is from the conversion server KS of the currently used codec - eg the codec according to ITU-T standard G.723 - based on information that is present in both the incoming signaling and in the incoming payload, determined and the corresponding digitized and encoded DTMF dial signal DSD8 selected.

In a third step 13 Now the first incoming data packet A1 with the sequence number 1001 is discarded by the conversion server and in a fourth step the sequence number 1001 of the first incoming data packet A1 is stored in a memory ZS on the conversion server KS. The value of the stored sequence number 1001 is now used as the starting position for the insertion of the digitized and encoded DTMF selection signal DSD8 in the outgoing data stream.

In a fifth step 15 a first data packet D1 of the digitized and coded DTMF selection signal DSD8 is now inserted into the outgoing data stream. In this case, the first data packet D1 is provided with the value of the sequence number 1001 stored in the memory ZS and the value in the memory ZS is increased by one. In a sixth step 16 a second incoming data packet A2 with the sequence number 1002 is discarded. In a seventh step 17 Now, a second data packet D2 of the digitized and encoded DTMF dial signal DSD8 is inserted in the outgoing data stream. In addition, the second data packet D2 becomes the seventh step 17 provided with the value stored in the memory ZS as a sequence number and the values in the memory ZS again increased by 1. The seventh step 17 is now repeated until all remaining data packets D3, ..., D120 of the digitized and encoded DTMF dial signal DSD8 have been inserted into the outgoing data stream. During this insertion process, all further, incoming data packets A3,... Are discarded by the conversion server. This means that as long as data packets D3, ..., D120 of the digitized and coded DTMF selection signal DSD8 are inserted into the outgoing data stream by the conversion server KS, the incoming data packets A1, A2, A3, ... are discarded.

2 shows by way of example the forwarding of incoming data packets A10, A11, A12,... from the first side S1 to the second side S2, after in a first step 21 the last data packet D120 of the digitized and coded DTMF selection signal DSD8 has been inserted into the outgoing data stream with a sequence number 1120. The value of sequence number 1120 was stored in memory ZS and is at this first step 21 increased by 1. In a second step 22 a first data packet A10 arriving on the first side S1 with a first sequence number 1110 is accepted by the conversion server and in a third step 23 forwarded to the second page S2. At this step 23 the first sequence number 1110 of the first data packet A10 is changed to the value 1121 stored in the memory ZS and the value in the memory ZS is again increased by one. In a fourth step 24 a second, incoming data packet A11 with a second sequence number 1111 is accepted by the conversion server KS. This second data packet A11 then becomes a fifth step 25 forwarded to the second side S2, wherein again the second sequence number 1111 changed to the value stored in the memory ZS value and the value in the memory ZS is increased by 1. These steps 22 . 23 respectively. 24 . 25 are carried out for all other incoming data packets A12, A13, ..., until again on the first page S1 in the course of signaling an outband message DS8, in the information about a dial digit, for example, the number 8 is included arrives.

at the method according to the invention was added note that S1 does not always contain data packets A1 on the first page, A2, A3, ... e.g. in the case of a so-called "silence suppression" in this case it is important that the sequence numbers 1001, 1002, 1003, .... of the data packets sent on the second side S2 A0, D1, D2, ... are correct, so that the data packets A0, D1, D2, A10, A11, etc. at the receiver can be put in the right order.

Claims (5)

Method for inserting DTMF dialing signals (DSD8) into a data stream comprising data packets (A1, A2, A3,...), In which encoded payload information is contained, characterized in that the possible DTMF dialing signals (DSD8) are stored in digitized and coded form, in that they are provided as data packets (D1, D2, D3, ...) instead of the payload-containing Da packet packets (A1, A2, A3, ...) are inserted into the data stream in such a way that data packets (A1, A2, A3,...) with useful information are discarded during the feed-in process, that a number of the inserted data packets (D1, D2 , D3, ...) of a DTMF dialing signal (DSD8) is determined and that after the feed operation, the identifier (1110, 1111, 1112, ...) of the data packets (A11, A12, A13, ...) with payload information in appropriate form is modified. Method according to claim 1, characterized in that that for the transfer of the payload data stream as a protocol's real-time Transport Protocol RTP is used. Method according to one of claims 1 to 2, characterized that as an identifier (1001, 1002,...) of the data packets (A1, A2, A3, D1, D2, D3, ...) in the data stream a sequence number - a so-called sequence number or a timestamp is used. Apparatus for carrying out a method according to the claims 1 to 3, characterized in that means for Insert from potential DTMF dialing signals (DSD8) in digitized and coded form as data packets (D1, D2, D3, ...) in the data stream instead of data packets (A1, A2, A3, ...) are provided with payload information, that means to Determine the number of inserted data packets (D1, D2, D3, ...) of a DTMF dialing signal (DSD8) and that means for modifying the identifier (1110, 1111, 1112, ...) of the data packets (A11, A12, A13, ...) with payload information are provided in a suitable form after the feeding process. Device according to claim 4, characterized in that that means for storing the possible DTMF dialing signals (DSD8) as samples in digitized and encoded form are.