A method comprising: receiving, by a packet broker of a visibility network, a first Internet Protocol, IP, Multimedia Subsystem, IMS, packet replicated from an IMS core network , wherein the first IMS packet is a Session Initiation Protocol, SIP, registration packet; adding, by the packet broker , a mapping between a public identity and a private identity associated with the first IMS packet to an identity table; and receiving, by the packet broker , a second IMS packet replicated from the IMS core network , wherein the second IMS packet is a SIP INVITE packet; the method being characterized by : identifying, by the packet broker , that the second IMS packet belongs to a new IMS session, wherein the identifying comprises: resolving FROM and TO public identities of the second IMS packet into corresponding FROM and TO private identities using the identity table; and in response to the resolving, determining that a combination of the FROM private identity, the TO private identity, and a call-ID associated with the second IMS packet is unique using a mapping table; generating, by the packet broker , a unique session identifier for the new IMS session for the second received IMS packet in response to the identifying; adding, by the packet broker , a combination of the FROM public identity, the TO public identity, the call-ID, and the generated unique session identifier to the mapping table; and adding, by the packet broker , the generated unique session identifier to the second received IMS packet. receiving, by a packet broker of a visibility network, a first Internet Protocol, IP, Multimedia Subsystem, IMS, packet replicated from an IMS core network , wherein the first IMS packet is a Session Initiation Protocol, SIP, registration packet; adding, by the packet broker , a mapping between a public identity and a private identity associated with the first IMS packet to an identity table; and receiving, by the packet broker , a second IMS packet replicated from the IMS core network , wherein the second IMS packet is a SIP INVITE packet; the method being characterized by : identifying, by the packet broker , that the second IMS packet belongs to a new IMS session, wherein the identifying comprises: resolving FROM and TO public identities of the second IMS packet into corresponding FROM and TO private identities using the identity table; and in response to the resolving, determining that a combination of the FROM private identity, the TO private identity, and a call-ID associated with the second IMS packet is unique using a mapping table; resolving FROM and TO public identities of the second IMS packet into corresponding FROM and TO private identities using the identity table; and in response to the resolving, determining that a combination of the FROM private identity, the TO private identity, and a call-ID associated with the second IMS packet is unique using a mapping table; generating, by the packet broker , a unique session identifier for the new IMS session for the second received IMS packet in response to the identifying; adding, by the packet broker , a combination of the FROM public identity, the TO public identity, the call-ID, and the generated unique session identifier to the mapping table; and adding, by the packet broker , the generated unique session identifier to the second received IMS packet. <EOS>