IMS call routing using tel-URIs

摘要

The present invention proposes a specific handling of tel URIs in an IMS terminating network so as to enable routing of calls using telephone numbers (and not SIP URIs with embedded telephone numbers) as identifiers of the target users of those calls. Specifically, the present invention introduces a conversion module which is located within the IMS terminating network and is capable of converting SIP URIs with embedded telephone numbers into equivalent tel URIs which are then used by a terminating I-CSCF and S-CSCF to query the SLF and/or HSS so that they can route the calls to the target users.

主权项

1. An Interrogating Call Session Control Function entity configured to route a Session Initiation Protocol (SIP) request in a terminating network towards a Serving Call Session Control Function entity, comprising:
a receiver configured to receive the SIP request; a processor configured to determine that the SIP request has a request Uniform Resource Identifier (URI) which includes a SIP URI with an embedded telephone number; a conversion module configured to generate a telephone number (tel URI) when said SIP URI contains a “phone-context” argument as follows:
extract a first set of digits located after the “phone-context” argument;extract a second set of digits located after a “sip:” in the SIP URI and before the “phone-context” argument;derive a third set of digits from the first set of digits and the second set of digits; andpre-pend a string “tel:” before the third set of digits to generate the tel URI; said processor configured to remove the SIP URI with the embedded telephone number and insert the tel URI in the request URI of the SIP request to form a revised SIP request; and a sender configured to submit the revised SIP request including the request URI with the tel URI towards the Serving Call Session Control Function.