Method for calling user terminal of IP multimedia subsystem

Abstract

The invention relates to a method for calling the user terminal of IP multimedia subsystem, which comprises: inquire-call control module (I-CSCF) inquires the register position of called user from the attached user server (HSS); I-CSCF, based on the response of HSS, sends the conversation initialize protocol (SIP) request to the service-call control module (S-CSCF); when the response of SIP request of S-CSCF to the I-CSCF is overtime, I-CSCF reselects S-CSCF and sends SIP request to S-CSCF. With said invention, if the non-registered S-CSCF does not feedback response caused by device accidence or communication interruption, I-CSCF can reselect other S-CSCF to treat the non-register service of IMS user, to improve the service quality.

Description

technical field [0001] The invention relates to a communication technology, in particular to a method for calling a user terminal of an IP multimedia subsystem. Background technique [0002] In an IMS (IP Multimedia Subsystem) network, when a UE (User Terminal) of an IMS user is called, the I-CSCF (query CSCF (call session control function module)) of the called network will pass Cx-Location- The Query command queries the HSS (Home Subscriber Server) about the registration location of the IMS user. [0003] If the IMS user has subscribed to an unregistered service (such as transfer to voice mailbox, etc.), when the IMS user is in the REGISTERED (registered) state, the HSS will return to the I-CSCF to process the registered service of the IMS user through the Cx-Location-QueryResp command The S-CSCF (serving CSCF), the I-CSCF sends a SIP (Session Initiation Protocol) request to the S-CSCF returned by the HSS, and the S-CSCF processes the registered service of the IMS user. ...

AI Technical Summary

Problems solved by technology

[0007] When the S-CSCF forwards the SIP request or processes the registered service or unregistered service of the IMS user, if the S-CSCF does not respond due to equipment failure or communication interruption, the session will time out and the SIP request on the calling side will fail with timeout (possibly causing call loss)

[0008] In addition, when the IMS user is in the REGISTERED state, the registered service of the called IMS user will not be able to be executed, and it is even impossible to provide the existing network-like "the user you are calling is temporarily unavailable, please dial later" network tips

[0009] When the called IMS user is in the UNREGISTERED state or the related ID is registered or the related ID is in the UNREGISTERED state, the unregistered service of the called IMS user will also be unable to perform, resulting in that the IMS network may not be able to serve the IMS user for a long time. Provide correct services (until the S-CSCF restores the service or the called IMS user successfully registers with other normal S-CSCFs after powering on, the IMS network can provide the correct services for the IMS user, and this process may last for a long time such as several hours, days, or even longer)

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