Method for reverse signalling for a transmission service which is to be used during a mobile terminated-PSTN/ISDN originated-call

A system in which a transmission service is backward-signaled, comprising:

• a destination mobile switching center in a digital mobile radio network, the destination mobile switching center having a service area;
• a mobile terminal in the service area;
• and
• a telecommunication network calling the mobile terminal via an access mobile switching center, the telecommunication network being an ISDN, a Public Switched Telephone Network (PSTN), or a Public Land Mobile Network (PLMN), wherein
• the destination mobile switching center sends an initial Bearer Capability to the mobile terminal;
• the mobile terminal and the destination mobile switching center negotiate information describing a transmission service to be used for a call to be set up between the telecommunication network and the mobile terminal, so as to revise the initial Bearer Capability and determine a revised Bearer Capability,
• the destination mobile switching center converts the revised Bearer Capability into an Integrated Services Digital Network (ISDN) User Part (ISUP)-compliant (ISDN-BC) information element,
• the Integrated Services Digital Network (ISDN) User Part (ISUP)-compliant (ISDN-BC) information element is transported using at least one ISUP message, from the destination mobile switching center to the access mobile switching center to effect the backward signaling, and
• call setup is not completed until after the Integrated Services Digital Network (ISDN) User Part (ISUP)-compliant (ISDN-BC) information element is transported to the access mobile switching center.

A destination mobile switching center in a digital mobile radio network for communicating between an access mobile switching center and a mobile terminal within a service area of the destination mobile switching center, the destination mobile switching center comprising:

• a negotiation unit to send an initial Bearer Capability to the mobile terminal, to negotiate information describing a transmission service to be used for a call to be set up between a telecommunication network and the mobile terminal, and to revise the initial Bearer Capability and determine a revised Bearer Capability;
• a conversion unit to convert the revised Bearer Capability into an Integrated Services Digital Network (ISDN) User Part (ISUP)-compliant (ISDN-BC) information element;
• and
• a transmitter to transmit the Integrated Services Digital Network (ISDN) User Part (ISUP)-compliant (ISDN-BC) information element using at least one ISUP message to the access mobile switching center to effect the backward signaling, wherein
• the telecommunication network is an ISDN, a Public Switched Telephone Network (PSTN), or a Public Land Mobile Network (PLMN), and
• call setup is not completed until after the Integrated Services Digital Network (ISDN) User Part (ISUP)-compliant (ISDN-BC) information element is transmitted to the access mobile switching center.