Method and apparatus for routing emergency services calls in an intelligent network

• US 20020054667A1
• Filed: 10/12/2001
• Published: 05/09/2002
• Est. Priority Date: 12/22/1997
• Status: Active Grant

• Current Assignee: RPX Clearinghouse LLC (RPX Corporation)
• Original Assignee: Celltech Group Limited (UCB SA)
• Inventors: Martinez, Edgar
• Granted Patent: US 6,721,395 B2
• Time in Patent Office: Days
• US Class Current: 379/45
• CPC Class Codes: H04M 2242/04 for emergency applications
• CPC Class Codes: H04Q 3/0029 Provisions for intelligent networking
• CPC Class Codes: H04W 4/90 Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS]
• CPC Class Codes: H04W 76/50 for emergency connections

Abstract

Emergency services calls may be alternate-routed in an intelligent network having at least one Service Control Point (SP) with access to a routing table, a plurality of Service Switching Points (SSP) equipped with point-in-call triggers and one or more emergency services stations (PSAP) The routing table lists a routing number for each of the emergency services stations. The method comprising the steps of:

(i) at a Service Switching Point, presetting a point—in-call trigger to operate at a predetermined point in a call for emergency services,

(ii) subsequently, during processing of an emergency services call, interrupting processing of the call and transmitting to the SCP a query signalling message requesting routing information,

(iii) at the SCP, accessing the routing table in dependence upon parameters in the query signalling message and obtaining a routing number for a selected emergency services operator station, forming a response signalling message including the routing number and returning such response signalling message to the SSP,

(iv) at the SSP, detecting the routing number, and routing the call to the emergency services operator station. There is also provided a method of translating signalling message parameters from a mobile protocol to an intelligent network protocol, and vice versa, to enable emergency services calls from mobile users to be routed to one or more PSAPs in the network.

Claims

1. A method of handling emergency services calls in an intelligent network having at least one Service Point (SP) equipped with software for providing service features and having access to databases including a routing table, a plurality of Service Switching Points (SSP) equipped with call processing software having point-in-call triggers for interrupting processing of a call and exchanging TCAP signalling messages with the Service Point to obtain instructions for further processing of the call, and one or more emergency services operator stations (PSAP), the Service Switching Points and Service Point being interconnected by an SS7 signalling system, the Service Switching Points being interconnected by trunks for calls therebetween, and the one or more emergency services operator stations being each connected by trunks or lines to a respective one of said Service Switching Points, the said routing table listing a routing number identifying a network location for each of said one or more emergency services operator stations, the method comprising the steps of:

(i) at a particular Service Switching Point, presetting a point-in-call trigger to operate at a predetermined point in a call for emergency services,

(ii) subsequently, when said particular Service Switching Point is processing an emergency services call, interrupting processing of the call and transmitting to the Service Point a query signalling message requesting routing information,

(iii) at the Service Point, upon receipt of the query signalling message, accessing said routing table in dependence upon parameters in the query signalling message and obtaining a routing number corresponding to a selected emergency services operator station, forming a response signalling message including the routing number and returning such response signalling message to said particular Service Switching Point,

(iv) at said particular Service Switching Point, upon receipt of said response signalling message, detecting the routing number, and routing the call to the emergency services operator station.

2. A method according to claim 1, wherein the point-in-call trigger is selected to operate following failure of an initial call completion attempt, and the method includes the steps, at the Service Switching Point, of attempting to complete the emergency services call on the basis of the dialled digits received from the calling party, and detecting that the initial call did not complete, said step of transmitting said query signalling message being contingent upon such step of detecting that the initial call did not complete.

3. A method according to claim 1, wherein the point-in-call trigger is set to interrupt all calls upon receipt of dialled digits from the calling party identifying that the call is for an emergency services station.

4. Apparatus for handling emergency services calls in a telecommunications network employing TCAP signalling, comprising at least one Service Point equipped with software for providing service features and having access to databases including a routing table, a plurality of Service Switching Points equipped with call processing software having point-in-call triggers for interrupting processing of a call and exchanging TCAP signalling messages with the Service Point to obtain instructions for further processing of the call, and one or more emergency services operator stations, the Service Switching Points and Service Point being interconnected by an SS7 signalling system, the Service Switching Points being interconnected by trunks for calls therebetween, and each of the emergency services operator stations being connected by trunks to a respective one of said one or more of the Service Switching Points, the routing table listing a routing number for each of said one or more emergency services operator stations;

each Service Switching Point comprising

(i) means for presetting a point-in-call trigger to operate at a predetermined trigger detection point in the precessing of a call for emergency services, and

(ii) means operative during processing of a call for emergency services to interrupt processing of the call in response to said trigger and transmit to the Service Point a signalling message requesting routing information,

each Service Point comprising

(iii) means operative, upon receipt of said signalling message, for accessing said routing table in dependence upon parameters in said signalling message and obtaining a routing number corresponding to a selected emergency services operator station, forming a response signalling message including the routing number and returning such response signalling message to the requesting Service Switching Point, each Service Switching Point further comprising

(iv) means operative, upon receipt of said response signalling message, for routing the call to the network address for completion to the emergency services station.

5. Apparatus according to claim 4, wherein each Service Switching Point comprises means operative to attempt to complete the emergency services call on the basis of digits dialled by the caller and identifying that the call is for an emergency services station, and the point-in-call trigger is set to interrupt call processing upon failure of such attempt.

6. Apparatus according to claim 4, wherein said trigger is set to interrupt all calls upon receipt, from the originating station, of dialled digits identifying that the call is for an emergency services station.

7. In a telecommunications network comprising a Service Point (SP), a plurality of Service Switching Points (SSP), one or more Public Service Access Points (PSAP) and a Signal Mediation point (SMP), and a mobile network portion comprising a Mobile Services Switching Centre (MSC) for routing calls from mobile users in cell sites associated with such MSC and Home Location Register (HLR), the MSC and SSPs being interconnected by trunks for routing calls therebetween, the SC and SSPs being connected to the SMP by Signalling System No. 7 (SS7) signalling links, the SMP being connected to the SCP and the HLR by respective SS7 links, the SP having access to a routing table including entries correlating routing numbers of PSAPs with cell site identifiers, the SMP having basic SCP software for handling mobile or wireline TCAP messages and additional conversion software and tables for translating TCAP message parameters according to mobile protocols to TCAP message parameters using intelligent network protocols, and vice versa,

the method comprising the steps of:

at the MSC;

upon receipt of a 9-1-1 call from a mobile station, forming a TCAP query message addressed to the destination point code of the HLR and routing the message to the SMP, the message including a mobile identification number (MIN) for the mobile station, a cell site number, and a mobile network address for the MSC, and the dialled digits,

at the SMP;

detecting the dialled digits identifying the call as an emergency services call;

translating the parameters in the message as received into corresponding AIN/IN parameters according to the intelligent network protocol being used by the SP,

forming an AIN/IN TCAP message including the translated parameters, the network address of the MSC and the cell site number being combined in an original Calling Party number,

overriding the destination point code of the HLR and routing the message to the SP,

at the SP,

accessing the mobile routing table using the original Calling Party number from the received query and obtaining a routing number for a PSAP,

including the PSAP routing number in a TCAP response message and sending this response message to the SMP,

at the SMP,

translating the intelligent network parameters of the TCAP response message into corresponding mobile network parameters,

and routing the response message to the MSC, at the MSC,

extracting the PSAP routing number from the TCAP message and routing the emergency services call thereto via one or more of the SSPs.

8. Signal Mediation Point apparatus comprising SS7 software for processing TCAP messages and conversion software for translating parameters of such TCAP messages formulated according to one mobile protocol into parameters according to a different intelligent network protocol, and vice versa, the SMP having signalling links for connection to a Mobile Switching Centre, a Service Point (SP) and a Home Location Register, the conversion software being operative, upon receipt of a query from the MSC containing a destination point code for the HLR and dialled digits of an emergency services call to detect said digits, translate the parameters into corresponding intelligent network parameters, override the destination point code of the HLR and route the message to the SP, and on receipt of a response from the SP, translate the parameters into corresponding mobile network parameters, and route the response message to the MSC.

9. Apparatus according to claim 8, wherein the conversion software is operative to determine a network address of the mobile switching centre and a cell site identifier and combine both into an Original Calling Party number in the intelligent network TCAP message sent to the SP.