Method and Apparatus for Charging

A method performed by a first session management function (SMF) in a visited network, comprising:

• sending to a second SMF in a home network a protocol data unit (PDU) session create request to establish a PDU session;
• receiving from the second SMF in the home network a PDU session create response comprising a first charging identifier of the second SMF in the home network for the PDU session;
• and
• sending to a first charging function in the visited network a first charging data request comprising the first charging identifier, a second charging identifier and a network function instance identifier of the second SMF.

A first session management function (SMF) configured for operation in a visited network, comprising:

• a processor;
• and
• a memory coupled to the processor, said memory containing instructions executable by said processor, whereby said first SMF is operative to:
• send to a second SMF in a home network a protocol data unit (PDU) session create request to establish a PDU session;
• receive from the second SMF in the home network a PDU session create response comprising a first charging identifier of the second SMF in the home network for the PDU session;
• and
• send to a first charging function in the visited network a first charging data request comprising the first charging identifier, a second charging identifier and a network function instance identifier of the second SMF.

A first charging function configured for operation in a visited network, comprising:

• a processor;
• and
• a memory coupled to the processor, said memory containing instructions executable by said processor, whereby said first charging function is operative to:
• receive from a first session management function (SMF) in the visited network a first charging data request comprising a first charging identifier for a protocol data unit (PDU) session, a second charging identifier for the PDU session and a network function instance identifier of a second SMF, wherein the first charging identifier is allocated by the second SMF in a home network and the second charging identifier is allocated by the first SMF in the visited network;
• and
• update a charging data record based on the first charging data request.