Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1999-05-11
2003-02-18
Chin, Vivian (Department: 2682)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S392000, C370S352000, C455S445000, C455S432300
Reexamination Certificate
active
06522655
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method in a telecommunications network for use in management and/or control of a call between two transceivers. The invention relates further to an arrangement and an apparatus for use in a telecommunications network for performing call management and/or control operations.
BACKGROUND OF THE INVENTION
A cellular radio telecommunication system or a Public Land mobile Network (PLMN) comprises a Mobile Services Switching Centre (MSC) for controlling and/or managing communications of a Mobile Station (MS) connected to the network system. The Mobile Station (MS) communicates with the MSC through a Base Station Subsystem (BSS), to which the MS is connected over a radio (i.e. air) interface between a Base Station (BS) of the Base Station Subsystem (BSS) and the MS. The MSC includes databases so as to enable an operation of the system. The databases are such as a Home Location Register (HLR) and a Visitor Location register (VLR) and additional databases for further subscriber information and billing operations etc.
MSCs can be divided e.g. to Visited MSCs (VMSC) and Transit MSCs (TMSC) or Gateway MSCs (GMSC). From these the VMSC is a MSC which used by a subscriber who is having a connection to a base station connected to this particular MSC. The TMSCs or the GMSCs are, in turn, used as nodes for possible routing and switching operations in the communications path between, i.e. intermediate, two VMSCs, or between a VMSC and any other exchange or switching point, or even between two TMSCs. Therefore, when a call is established between two mobile stations, the call is also accomplished between an originating VMSC and a terminating VMSC, and there may be one or several intermediate MSCs between the VMSCS.
In the mobile radio telecommunications systems or the PLMN the speech and other messaging is coded in the transmitting Mobile Station or similar transmitting and receiving terminal (transceiver), such as voice mail box, before the transmission thereof by using an appropriate coding technique. For example, in Personal Digital Cellular (PDC) system a VSELP (Vector Sum Excited Linear Prediction) 11.2 kbit/s speech coding is used on the full rate channel and a PSI-CELP (Pitch Synchronized Innovation—Excited Linear Prediction) 5.6 kbits/s speech coding is used on the half rate channel over an air or radio interface to the Base Station.
When having a speech call from a PLMN to a fixed network, such as to a Public Switched Telephone Network (PSTN), or to an Integrated Digital Services Network (ISDN), a transcoder or codec is connected to the originating Mobile Services Switching Centre (VMSC) controlling the radio interface between the BSS and the calling mobile station. The transcoder is used to convert the VSELP/PSI-CELP coded speech to a PCM (Pulse Code Modulation) &mgr;-law coded speech so as to enable communication towards the PSTN.
When having a connection between two mobile transceiver stations, the VSELP/PSI-CELP coded speech is transmitted transparently over the PLMN network. In this instance the transcoders are through connected during the connection so as to avoid a conversion of e.g. a VSELP/PSI-CELP coded speech to a PCM &mgr;-law coded speech and then back to VSELP/PSI-CELP coded speech, which would decrease the speech quality at the receiving end.
However, the transcoders are active, i.e. converting the VSELP/PSI-CELP coded speech to the PCM &mgr;-law coded speech during the call setup in order to enable listening of announcements and tones from the telephone network. After the setup is completed, the transcoders are changed or switched to the through connected mode by means of a specific codec control signalling by using a Mobile Application Part (MAP) over a system
7
signalling (#SS
7
).
There are PLMN arrangements, such as the PDC, in which the codec control signalling occurs as end-to-end signalling, i.e. the air interface is coded from one end to the other. The messages are addressed with a Network Code (NC) and a Signalling Point Code (SPC) of the designated Visited Mobile Services Switching Centre (VMSC). The addresses are carried in an ISUP (Integrated Services Digital Network User Part) signal as an IAM (Initial Address Message).
The codec control signalling is performed for basic calls only according to a DMNI (Digital Mobile Communications Network Internode Interface) standard. For example, at forwarded calls the codec control is not performed, but the PCM &mgr;-law speech coding is always used between the originating VMSC and the terminating VMSC. This, however, causes a remarkable decrease in speech quality.
Since the codec control signalling occurs as an end-to-end signalling, the intermediate nodes or connection points, like transit exchanges or MSCs or Service Switching Points (SSP) providing Intelligent Network (IN) services, are not able to know the speech coding used in the communications. This is a disadvantage e.g. in cases where monitoring equipment or similar, or an announcement should be connected to the call. As the coding in use is not exactly known, the system is not aware of the coding by which announces, messages, information, tones etc. should be transmitted to the mobile station(s) or which coding should be used to decode received announces, tones, control messages etc. In addition, it is not possible to affect and control the used coding during the connection (e.g. it is not possible to change the mode of the coding e.g. from VSELP to &mgr;-law coding during the call), which might be required e.g. in cases where a conference call with a third party should be set up during an already existing call between two parties. In case this information is to be transmitted separately from the terminating (or originating) VMSC to the intermediate node later on during or after the setup, a separate and additional messaging arrangement for this is needed.
SUMMARY OF THE INVENTION
It is an object of the present invention to overcome the disadvantages of the prior art solutions and to provide a new type of solution for controlling and/or managing a call using end to end signalling.
An object of the present invention is to provide a solution by means of which the management and monitoring of calls is made easier to accomplish in the intermediate nodes of a Land Mobile Network.
An object of the present invention is to provide a solution by means of which unnecessary coding/decoding in a call between two transceivers communicating through a cellular system is avoided.
An object of the present invention is to provide a solution by means of which a delay and/or additional signalling in switching additional features and/or services to a call implemented by means of end-to-end signalling is avoided.
An object of the present invention is to provide a solution in which speech quality of a call between two mobile stations is improved.
An object of the present invention is to provide a solution by means of which switching operations, such as switching a call to Intelligent Network service applications or switching of monitoring apparatus or announcements to a call, can be eased.
The objects are obtained by a method of implementing a call in a telecommunications system, the call being routed from a first transceiver to a second transceiver via a first switching centre and a second subsequent switching centre, the method comprising:
including in a call setup message from the first switching centre to the second switching centre an address of said first switching centre;
intercepting the call setup message at a telecommunications node intermediate to the first and second switching centres;
replacing the address of the first switching centre in the setup message from the first switching centre with an address of the intermediate node;
forwarding the call set up message transmission to the second switching centre; and
sending a response message including call set up information and using end to end signalling from said second switching centre, said response message using said substitute address of the intermediate n
Chin Vivian
Lee John J
Nixon & Vanderhye PC
Telefonaktiebolaget LM Ericsson (publ)
LandOfFree
Method and apparatus in a telecommunications system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus in a telecommunications system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus in a telecommunications system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3147216