Roaming from IMS domain to the CS domain
First Claim
1. A method of routing a terminated call to a subscriber from an Internet Protocol based domain to a circuit switched domain, wherein said Internet Protocol based domain has call state control functionalities implemented, said method comprising the steps of receiving an invitation of said subscriber for a call by at least one call state control functionality within said Internet Protocol based domain;
- obtaining the profile of said subscriber from said home subscriber serving means to a call state control functionality;
requesting further routing information from said home subscriber serving means;
requesting a switching means within said circuit switched domain currently visited by said subscriber for said roaming number by said home subscriber serving means;
returning said roaming number of said subscriber to said home subscriber serving means by said visited switching means;
returning said roaming number as said further routing information from said home subscriber serving means to said call state control functionality; and
establishing said call via gateway means for connecting said domains as well as via said visited switching means to said subscriber.
1 Assignment
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Accused Products
Abstract
A method of routing a terminated call to a subscriber from an Internet Protocol based domain (IMS) to a circuit switched domain (CS), wherein said Internet Protocol based domain (IMS) has call state control functionalities implemented, said method comprising the steps of receiving an invitation (S1) of said subscriber for a call by at least one call state control functionality within said Internet Protocol based domain (IMS); obtaining (S5) the profile of said subscriber from said home subscriber serving means (HSS) to a call state control functionality (S-CSCF); requesting (S7) further routing information from said home subscriber serving means (HSS); requesting (S9) a switching means (VMSC) within said circuit switched domain (CS) currently visited by said subscriber for said roaming number by said home subscriber serving means (HSS); returning (S10) said roaming number of said subscriber to said home subscriber serving means (HSS) by said visited switching means (VMSC); returning (S12) said roaming number as said further routing information from said home subscriber serving means (HSS) to said call state control functionality (S-CSCF); and establishing (S131-S133) said call via gateway means (BGCF, MGCF) for connecting said domains (IMS, CS) as well as via said visited switching means (VMSC) to said subscriber.
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Citations
9 Claims
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1. A method of routing a terminated call to a subscriber from an Internet Protocol based domain to a circuit switched domain, wherein said Internet Protocol based domain has call state control functionalities implemented,
said method comprising the steps of receiving an invitation of said subscriber for a call by at least one call state control functionality within said Internet Protocol based domain; -
obtaining the profile of said subscriber from said home subscriber serving means to a call state control functionality;
requesting further routing information from said home subscriber serving means;
requesting a switching means within said circuit switched domain currently visited by said subscriber for said roaming number by said home subscriber serving means;
returning said roaming number of said subscriber to said home subscriber serving means by said visited switching means;
returning said roaming number as said further routing information from said home subscriber serving means to said call state control functionality; and
establishing said call via gateway means for connecting said domains as well as via said visited switching means to said subscriber. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A home subscriber serving device capable of using routing information for terminating a call to a subscriber, comprising
an IP multimedia part and a home location registering part interfaced to each other, wherein said home location registering part comprises transceiver means, capable of requesting and receiving roaming numbers from the circuit switched domain.
Specification