A METHOD OF RESTRUCTURING A CALL SIGNAL FRAME IN A CELLULAR MOBILE TELEPHONE SYSTEM

THE PRESENT INVENTION RELATES TO A METHOD FOR AVOIDING THE USE OF SPECIALLY ALLOCATED, TEMPORARY ROAMING NUMBERS IN A MOBILE TELEPHONE SYSTEM FOR ROUTING OUTSIDE OUTSIDE CALLS TO A MOBILE SUBSCRIBER (MS) ROAMING IN THE SYSTEM.ACCORDING TO THE INVENTION, AN INCOMING STANDARDIZED CALL SIGNAL FRAME (IAM) COMPRISING A FIRST PARAMETER FIELD (CALLED PART ADDRESS) INCLUDING A DIRECTORY NUMBER (MSN) IS CONSTRUCTED. THE DIRECTORY NUMBER (MSN) IN THE FIRST PARAMETER FIELD IS REPLACED WITH THE UNIQUE ROUTING NUMBER (PRN) OF THE MOBILE TELEPHONE SWITCHING CENTRE (MSC/GSM) WITHIN WHOSE SERVICE AREA THE MOBILE SUBSCRIBER (MS) ROAMS. A UNIQUE INTERNATIONAL MOBILE SUBSCRIBER INDENTITY (IMSI) AND THE DIRECTORY NUMBER (MSN) ARE INSERTED IN A SECOND PARAMETER FIELD (END INFORMATION TRANSFER, EIT). THIS IMPLIES A STATIC ADDRESSING PRINCIPLE IN WHICH THE ROUTING ADDRESS WILL ALSO CONTAIN DIRECTLY THE NUMBER (MSN OR IMSI) OF THE CALLED SUBSCRIBER. THIS FACILITATES RESTORATION OF CERTAIN REGISTERS (HLR, GLR) AFTER A FAILURE.(FIG. 1)