Patent ID: 11936694
Assignee: T-MOBILE USA, INC.
Field: Digital communication (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A method for routing a communication session initiated in an Internet Protocol (IP) Multimedia Subsystem (IMS), comprising:
receiving, by a Breakout Gateway Control Function (BGCF) node operating in a first domain, a first message from a caller requesting an establishment of a call session;
determining, by the BGCF node based on header information of the first message, that the caller is located in a second domain different than the first domain; and
directing, by the BGCF nodes, without a Call Session Control Function (CSCF) network server querying an Electronic Numbering (ENUM) server, the first message to a specific destination server to complete the establishment of the call session based on a preconfigured rule,
wherein the preconfigured rule represents an agreement between a first carrier of the first domain and a second carrier of the second domain, the agreement indicating that a subset of calls from the second domain is routed by the first domain,
wherein the directing comprises, upon determining that a call number of the caller is valid:
determining, by the BGCF node, whether the call number of the caller is a ported number, and
generating, by the BGCF node, a second message based on the preconfigured rule, wherein the second message comprises a routing number field formed by adding one or more routing digits to (1) the call number carried in the first message in response to the call number not being a ported number, or (2) a local routing number assigned to the caller in case the call number being a ported number.