Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
2000-08-28
2001-05-01
Chang, Vivian (Department: 2682)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S433000
Reexamination Certificate
active
06226517
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
This invention relates to telecommunication systems and, more particularly, home location register (HLR) and to a method of routing a call directed to a portable directory number in a radio telecommunications network.
2. Description of Related Art
Number portability (service provider portability) allows subscribers to retain their directory numbers (DNs) as the subscribers “port” from one service provider to another. In a radio telecommunications network, when a call is placed to a portable DN, the originating mobile switching center (MSC) must send a query known as a Number Portability Request (NPREQ) to a Number Portability Database (NPDB) to obtain a routing address for that portable DN. However, when the call originates in a MSC that “owns” the DN, sending the NPREQ may not be necessary, and may be a waste of time and system resources. In this case, the MSC should send a routing number query such as a Location Request (LOCREQ) Invoke message to the home location register (HLR) to obtain a routing number. However, there is currently no process by which the MSC may give priority to one of the two queries (LOCREQ or NPREQ), or salvage a call if the chosen query does not return a useful result.
In order to overcome this disadvantage, it would be advantageous to have a method of prioritizing the LOCREQ and NPREQ queries, and salvaging a call if the chosen query does not return a useful result. The present invention provides such a method.
SUMMARY OF THE INVENTION
In one aspect, the present invention is a home location register (HLR) for providing a routing number to an originating mobile switching center (O-MSC) when an incoming call is directed to a portable directory number in a radio telecommunications network. The network includes a Number Portability Database (NPDB) that stores a plurality of location routing numbers (LRNs). The HLR includes a signaling mechanism that (1) receives from the O-MSC, a first routing number request that includes a dialed directory number; (2) sends to the NPDB, a second routing number request that includes the dialed directory number; (3) receives from the NPDB, an LRN assigned to the dialed directory number in response to the second routing number request; and (4) sends to the O-MSC, the LRN in response to the first routing number request. The HLR also includes means for determining whether a routing number is assigned to the dialed directory number. The routing number determining means directs the signaling mechanism to send the second routing number request to the NPDB upon determining that a routing number is not assigned to the dialed directory number.
In another aspect, the present invention is a method of routing a call directed to a portable directory number in a radio telecommunications network which begins by sending a first routing number request from the O-MSC to the HLR, the first routing number request including a dialed directory number. This is followed by determining in the HLR whether a routing number is assigned to the dialed directory number, and sending a second routing number request which includes the dialed directory number from the HLR to the NPDB upon determining that a routing number is not assigned to the dialed directory number in the HLR. This is followed by retrieving from the NPDB, a location routing number (LRN) assigned to the dialed directory number, sending the LRN from the NPDB to the HLR in a first response message, sending the LRN from the HLR to the O-MSC in a second response message, and routing the call to the LRN.
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Bishai Nadia
Britt Margaret
Chang Vivian
Nguyen Duc
Smith ,Danamraj & Youst, P.C.
Telefonaktiebolaget L M Ericsson (publ)
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