Abstract: A method performed by a first network node in a Visited Public Land Mobile Network, VPLMN. The first network node is related to Lawful Intercept, LI, in the VPLMN. The first UE is associated with a Home Public Land Mobile Network, HPLMN and is located in the VPLMN. When the communication is started, the first network node receives a first Session Initiation Protocol, SIP, message from a gateway node in the VPLMN. The first SIP message includes first data related to starting of the communication. The first network node determines, based on analysing the first data, first communication data. The first network node sends a first request to a second network node operating in the VPLMN. The first request includes the determined first communication data and requests a first action to be performed by the second network node.

Abstract: A permissioned blockchain is used in a lawful interception, LI, context. Participants include a law enforcement agency, LEA, function, a LI mediation and delivery function, MF/DF, and an intercepting network function. A smart contract registered in the blockchain includes conditions associated with intercept related information, IRI, and/or communication content, CC, transactions. Registration is made in the blockchain of IRI and/or CC transactions performed by the participants during LI of a communication between two entities in a telecommunication network. The registered IRI and/or CC transactions are propagated among the participants and the smart contract is executed to verify whether or not the registered IRI and/or CC transactions are compliant with the smart contract. The participants are then informed about whether or not the registered IRI and/or CC transactions are compliant with the smart contract.