Method for correlating in a Lawful Intercept Mediation system, LIMS, received Intercept Related Information, IRI, and, Communications Content, CC, data packets of a target's lawfully intercepted session for deliverance over HI2 and HI3 interfaces, respectively, by means of a session-specific Correlation Identification Number, CIN, and wherein the CC data packets are received over an X3 interface, the method characterized by: - receiving an accounting server message of a first kind or a second kind; - acquiring from the received message a target identification data, a session ID, and a Framed-IP-address associated with the target; - creating the session-specific CIN using said acquired target identification data, the session ID, and the Framed-IP-address, if the accounting server message is of the first kind, - reading the target identification data and the Framed-IP-address of the CC data packets of a target's lawfully intercepted session received over the X3 interface; - creating a specific key, key1, using the read identification and the Framed-IP-address being the source-IP-address associated to the target; - identifying (S230;S235) the session-specific CIN by means of the specific key as memory address in a dedicated data storage; and if the key is found: - inserting the identified session-specific CIN in a HI3 message if a match of the key, key1, is found in the dedicated data storage; and if the first key is not found: - creating a second specific key, key2, using the read target identification data and the Framed-IP-address being the destination-IP-address associated to the target; - identifying the session-specific CIN by means of the second key, key2, as memory address in the dedicated data storage; - inserting the identified session-specific CIN in a HI3 message if a match of the second key, key2, is found in the dedicated data storage. - receiving an accounting server message of a first kind or a second kind; - acquiring from the received message a target identification data, a session ID, and a Framed-IP-address associated with the target; - creating the session-specific CIN using said acquired target identification data, the session ID, and the Framed-IP-address, if the accounting server message is of the first kind, - reading the target identification data and the Framed-IP-address of the CC data packets of a target's lawfully intercepted session received over the X3 interface; - creating a specific key, key1, using the read identification and the Framed-IP-address being the source-IP-address associated to the target; - identifying (S230;S235) the session-specific CIN by means of the specific key as memory address in a dedicated data storage; and if the key is found: - inserting the identified session-specific CIN in a HI3 message if a match of the key, key1, is found in the dedicated data storage; and if the first key is not found: - creating a second specific key, key2, using the read target identification data and the Framed-IP-address being the destination-IP-address associated to the target; - identifying the session-specific CIN by means of the second key, key2, as memory address in the dedicated data storage; - inserting the identified session-specific CIN in a HI3 message if a match of the second key, key2, is found in the dedicated data storage.