4.19 Support of Preferred Circuit Carrier Access and Per Call Circuit Carrier Selection

23.2283GPPIP Multimedia Subsystem (IMS)Release 18Stage 2TS

4.19.1 Preferred Circuit Carrier Access and Per Call Circuit Carrier Selection

Preferred Circuit Carrier Access allows the network operator to configure a preferred long distance circuit carrier for a subscriber, set of subscribers or all subscribers on the network. All long distance calls from a subscriber are routed to the long distance circuit carrier when preferred circuit carrier access applies. A SIP message parameter indicates the preferred circuit carrier selected. This parameter can be delivered to the PSTN. An application server can be used to insert preferred circuit carrier parameters. The BGCF needs to consider, and can insert, the preferred circuit carrier parameters when routing calls towards an MGCF.

Preferred Circuit Carrier Selection per call, also known as Dial-around, allows the subscriber to request a long distance carrier for a specific call. A dial-around request is dialled by the subscriber along with the called party number at call origination. As configured per operator policy, the dial-around circuit carrier selection can take precedence over other preferred circuit carrier selection that can be configured in the network. Therefore, based on operator policy, the preferred circuit carrier parameter is not to be replaced if already present in a SIP message with a dial-around indicator. A SIP message parameter indicates the preferred circuit carrier selected with a dial-around indicator. This parameter is delivered to the PSTN.

Support of preferred circuit carrier access and dial-around is optional within a network and is subject to, and configured per, operator policy.