Section: 5.3.4.4.2 Tracking of IMS NEs generating charging information
Content: Based on operator policy, each IMS NE for which the CTF is generating charging events, shall include its own address or specific NE identifier into the initial SIP request to be sent out within the trust domain. The final SIP response sent back by the last element of the trust domain shall contain the list of addresses and identifiers received within the initial SIP request. The list of addresses or identifiers received in the final response shall be included in the charging event generated by the CTF.