System and method for originating a call via a circuit-switched network from a user equipment device

Abstract

In one aspect, an application server (AS) node comprises a processor configured to receive a first SIP Invite request from the UE device, the first SIP Invite request having call information which includes a URI of a called party and data indicating that the first SIP Invite request is for a bearer over a circuit-switched (CS) network. An E.164 number is associated with the call information in the first SIP Invite request and a SIP response including the E.164 number is sent to the UE device in response to receiving the first SIP Invite request. When a call setup message including the E.164 number received from the CS network, the received E.164 number is verified if it is valid and if so, the call information is identified based on the E.164 number and is sent to the called party via a second SIP Invite request.

What is claimed is: 
     
       1. A method for an application server (AS) node, the method comprising:
 receiving a first SIP Invite request from a mobile communication device, the first SIP Invite request having call information which includes a call reference number, a uniform resource indicator (URI) of a called party and data used for determining whether the first SIP Invite request is for a bearer over a circuit-switched (CS) network; 
 associating an E.164 number with the call information in the first SIP Invite request; 
 sending a SIP alternative service response to the mobile communication device in response to receiving the first SIP Invite request, the SIP alternative service response including the E.164 number and the call reference number; 
 after sending the SIP alternative service response, receiving a call setup message from the CS network, the call setup message having the E.164 number; 
 verifying that the received E.164 number remains valid; 
 identifying the call information based on the E.164 number; and 
 sending, to the called party, a second SIP Invite request that includes the call information a second call information. 
 
     
     
       2. The method of  claim 1 , further comprising:
 identifying the URI of the called party in a TARGET field of the first SIP Invite request. 
 
     
     
       3. The method of  claim 1 , wherein a URI field of the first SIP Invite request is populated with a public service identifier (PSI) of the AS node of an Internet Protocol (IP) multimedia subsystem (IMS) network. 
     
     
       4. The method of  claim 1 , further comprising:
 reading the data; and 
 determining, based on the data, that the first SIP Invite request is for the bearer over the CS network. 
 
     
     
       5. The method of  claim 1 , wherein the call setup message is another SIP Invite request. 
     
     
       6. An application server (AS) node comprising:
 a processor configured to:
 receive a first SIP Invite request from a mobile communication device, the first SIP Invite request having call information which includes a call reference number, a uniform resource indicator (URI) of a called party and data used for determining whether the first SIP Invite request is for a bearer over a circuit-switched (CS) network; 
 associatingassociate an E.164 number with the call information in the first SIP Invite request; 
 send a SIP alternative service response to the mobile communication device in response to receiving the first SIP Invite request, the SIP alternative service response including the E.164 number and the call reference number; 
 after sending the SIP alternative service response, receive a call setup message from the CS network, the call setup message having the E.164 number; 
 verify that the received E.164 number remains valid; 
 identify the call information based on the E.164 number; and 
 send, to the called party, a second SIP Invite request that includes the call information a second call information. 
 
 
     
     
       7. The AS node of  claim 6 , wherein the processor is further configured to identify the URI of the called party in a TARGET field of the first SIP Invite request. 
     
     
       8. The AS node of  claim 6 , wherein the processor is further configured to select the E.164 number by allocating the E.164 number from a plurality of E.164 numbers. 
     
     
       9. The AS node of  claim 6 , wherein the processor is further configured to:
 read the data; and 
 determine, based on the data, that the first SIP Invite request is for the bearer over the CS network. 
 
     
     
       10. The AS node of  claim 6 , wherein the call setup message is another SIP Invite message. 
     
     
       11. The method of claim 1, wherein the second call information comprises a second call reference number.  
     
     
       12. The method of claim 1, wherein the second call information comprises a second uniform resource indicator (URI).  
     
     
       13. The method of claim 12, wherein the URI in the first SIP Invite is a first URI and the second URI is the first URI.  
     
     
       14. The AS node of claim 6, wherein the second call information comprises a second call reference number.  
     
     
       15. The AS node of claim 6, wherein the second call information comprises a second uniform resource indicator (URI).  
     
     
       16. The AS node of claim 15, wherein the URI in the first SIP Invite is a first URI and the second URI is the first URI.