Method for call establishment
First Claim
1. A method for call establishment in a cellular radio system comprising a first mobile services switching centre a cellular radio system home location register for storing subscriber and location data on subscribers in the cellular radio system, and a second mobile services switching centre, the method comprising the following steps:
- a private branch exchange connected to the second mobile services switching centre is provided, subscribers being located within the service area of said private branch exchange;
the home location register of the cellular radio system stores information on whether the subscriber is located within the service area of its home private branch exchange indicated with a home location area identifier;
the call to the subscriber and the telephone number of the subscriber are routed to the first mobile services switching centre;
the first mobile services switching centre requests the home location register to provide routing information of the subscriber;
if the subscriber is located within the service area of its home private branch exchange, in response to the routing information request placed by the first mobile services switching centre the home location register sends to the first mobile services switching centre a roaming number containing the home location area identifier of the subscriber and having a certain correspondence with the telephone number of the subscriber;
the first mobile services switching centre compares the roaming number of said subscriber with the telephone number of the subscriber and, in consequence, if said correspondence between the roaming number and the telephone number of the subscriber exists, the first mobile services switching centre sends an indication of the fact that said call is to be routed to the subscriber and that the subscriber is located within the service area of its home private branch exchange to the second mobile services switching centre, which has connection with the home private branch exchange within the service area of which the subscriber is located;
in response to said indication of the subscriber being located within the service area of its home private branch exchange sent by the first mobile service switching centre, the second mobile services switching centre does not perform the mobility management functions pertaining to normal connection establishment in the system and sends a connection establishment request to the private branch exchange of the home location area of the subscriber;
in response to the connection establishment request it has received the home private branch exchange of the subscriber performs the necessary mobility management functions and establishes a connection between the subscriber and the second mobile services switching centre.
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Accused Products
Abstract
The invention relates to a method for call establishment, wherein the home location register (HLR) of a cellular radio system stores information on whether a subscriber (CPP) is located within the service area of its home private branch exchange (PBX), the call to the subscriber is routed to a first mobile services switching center (GMSC), the first mobile services switching center requests (101) the home location register (HLR) to provide routing information of the subscriber, if the subscriber (CPP) is located within the service area of its home private branch exchange, the home location register sends (202) to the first mobile services switching center for comparison a roaming number having a certain correspondence with the telephone number of the subscriber, if said correspondence between the roaming number and the telephone number of the subscriber exists, the first mobile services switching center sends (203) to a second mobile services switching center (MSC) an indication of the fact that a call is to be routed to the subscriber and that the subscriber is located within the service area of its home private branch exchange (PBX), the second mobile services switching center (MSC) does not perform the mobility management functions pertaining to normal connection establishment in the system and sends (204) a connection establishment request to the private branch exchange of the home location area of the subscriber, which performs the necessary mobility management functions (215, 216, 217, 218) and establishes (119) a connection between the subscriber (CPP) and the second mobile services switching center.
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Citations
12 Claims
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1. A method for call establishment in a cellular radio system comprising a first mobile services switching centre a cellular radio system home location register for storing subscriber and location data on subscribers in the cellular radio system, and a second mobile services switching centre, the method comprising the following steps:
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a private branch exchange connected to the second mobile services switching centre is provided, subscribers being located within the service area of said private branch exchange; the home location register of the cellular radio system stores information on whether the subscriber is located within the service area of its home private branch exchange indicated with a home location area identifier; the call to the subscriber and the telephone number of the subscriber are routed to the first mobile services switching centre; the first mobile services switching centre requests the home location register to provide routing information of the subscriber; if the subscriber is located within the service area of its home private branch exchange, in response to the routing information request placed by the first mobile services switching centre the home location register sends to the first mobile services switching centre a roaming number containing the home location area identifier of the subscriber and having a certain correspondence with the telephone number of the subscriber; the first mobile services switching centre compares the roaming number of said subscriber with the telephone number of the subscriber and, in consequence, if said correspondence between the roaming number and the telephone number of the subscriber exists, the first mobile services switching centre sends an indication of the fact that said call is to be routed to the subscriber and that the subscriber is located within the service area of its home private branch exchange to the second mobile services switching centre, which has connection with the home private branch exchange within the service area of which the subscriber is located; in response to said indication of the subscriber being located within the service area of its home private branch exchange sent by the first mobile service switching centre, the second mobile services switching centre does not perform the mobility management functions pertaining to normal connection establishment in the system and sends a connection establishment request to the private branch exchange of the home location area of the subscriber; in response to the connection establishment request it has received the home private branch exchange of the subscriber performs the necessary mobility management functions and establishes a connection between the subscriber and the second mobile services switching centre. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification