Ims cross carrier supportability

A method, performed by one or more devices of a first Internet Protocol Multimedia Subsystem network, the method comprising:

• receiving, by at least one of the one or more devices, a first registration request for a first mobile directory number, associated with a subscriber, wherein the first mobile directory number corresponds to a home mobile directory number with respect to the first Internet Protocol Multimedia Subsystem network;
• registering, by at least one of the one or more devices, the first mobile directory number with the first Internet Protocol Multimedia Subsystem network;
• detecting, by at least one of the one or more devices, a service point trigger, associated with the subscriber, to register a second mobile directory number, foreign to the first Internet Protocol Multimedia Subsystem network, with a second Internet Protocol Multimedia Subsystem network, in response to the first mobile directory number being registered;
• and
• sending, by at least one of the one or more devices, a second registration request to the second Internet Protocol Multimedia Subsystem network, to register the second mobile directory number with the second Internet Protocol Multimedia Subsystem network.

A system comprising:

• an application server device, associated with a first Internet Protocol Multimedia Subsystem network, configured to:
• receive a first registration request for a mobile directory number associated with a user equipment device;
• identify a second Internet Protocol Multimedia Subsystem network, associated with the mobile directory number;
• send a second registration request for the mobile directory number to a Call Session Control Function device associated with the second Internet Protocol Multimedia Subsystem network;
• receive an authentication request from the Call Session Control Function device, in answer to the sent registration request;
• obtain an authentication value for the mobile directory number, in response to receiving the authentication request;
• send a third registration request for the mobile director number to the Call Session Control Function device with the obtained authentication value;
• and
• receive an indication from the Call Session Control Function device that a registration of the mobile directory number with the second Internet Protocol Multimedia Subsystem network has been successfully completed.