A method, comprising: receiving a first message in connection with a first communication session (212, 312) that spans one or more Back-to-Back User Agents, B2BUAs; assigning a first global session identifier to the first communication session, the first global session identifier corresponding to a token that identifies the first communication session end-to-end and remains unaltered even as the first communication session traverses the one or more B2BUAs; receiving a second message in connection with a second communication session (224, 324) that also spans the one or more B2BUAs; assigning a second global session identifier to the second communication session, the second global session identifier corresponding to a token that identifies the second communication session end-to-end and remains unaltered even as the second communication session traverses the one or more B2BUAs; examining a parameter of each of the first global session identifier and the second global session identifier, the parameter comprising at least one of a Session Initiation Protocol, SIP, REFER-To header, a SIP INVITE-Join R-URI, a SIP INVITE-Replace R-URI, a Contact header, a Call-Info header, an av-ouri parameter, and attachments of the second message for information which indicates the second communication session is logically associated with the first communication session; determining, at least in response to the examining step, that the first communication session and the second communication session are logically associated with one another; and in response to determining that the first and second communication sessions are logically associated with one another, configuring at least one message transmitted during at least one of the first and second communication session to indicate the association between the first and second communication sessions by inserting as an associated Global Session Identifier, GSID, the current GSID of the first session and the current GSID of the second session that is associated with the first session in the GSID header of the message. receiving a first message in connection with a first communication session (212, 312) that spans one or more Back-to-Back User Agents, B2BUAs; assigning a first global session identifier to the first communication session, the first global session identifier corresponding to a token that identifies the first communication session end-to-end and remains unaltered even as the first communication session traverses the one or more B2BUAs; receiving a second message in connection with a second communication session (224, 324) that also spans the one or more B2BUAs; assigning a second global session identifier to the second communication session, the second global session identifier corresponding to a token that identifies the second communication session end-to-end and remains unaltered even as the second communication session traverses the one or more B2BUAs; examining a parameter of each of the first global session identifier and the second global session identifier, the parameter comprising at least one of a Session Initiation Protocol, SIP, REFER-To header, a SIP INVITE-Join R-URI, a SIP INVITE-Replace R-URI, a Contact header, a Call-Info header, an av-ouri parameter, and attachments of the second message for information which indicates the second communication session is logically associated with the first communication session; determining, at least in response to the examining step, that the first communication session and the second communication session are logically associated with one another; and in response to determining that the first and second communication sessions are logically associated with one another, configuring at least one message transmitted during at least one of the first and second communication session to indicate the association between the first and second communication sessions by inserting as an associated Global Session Identifier, GSID, the current GSID of the first session and the current GSID of the second session that is associated with the first session in the GSID header of the message.