Communication networks and associated methods are disclosed that provide third party charging for SIP sessions. A communication network of the invention comprises a session control function (e.g., an IMS CSCF), a network node (e.g., an IMS application server), and a charging system. The session control function serves a SIP session initiated between a first and second party. The network node identifies a third party to charge for the session. The network node includes a third party identifier for the third party in a SIP message for the session, and transmits the SIP message to the session control function. The session control function generates a charging message, maps the third party identifier to the charging message, and transmits the charging message that includes the third party identifier to the charging system. The charging system then initiates charging of the session to the third party based on the third party identifier.