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33 series - Lawful interception

33.108 - 3G security; Handover interface for Lawful Interception (LI) 33.107 - 3G security; Lawful interception architecture and functions 33.106 - Lawful interception requirements Up to the 33 series


Lawful interception is the ability of a law enforcement agency to intercept the telecommunications traffic associated with a particular user, in accordance with the relevant national & regional laws and technical regulations.

The diagram shows the two main interfaces that are associated with lawful interception:

  • Internal network interface: This is within the network. The administration function sends configuration messages to the individual network nodes, which respond by sending communication traffic and intercept-related information to the mediation functions. The information carried by the INI is defined by 3GPP.
  • Handover interface: This is between the LEMF and the network. It carries similar information to the INI, but the information is defined and formatted in accordance with the relevant laws and technical regulations.

The purpose of the administration and mediation functions is to convert information between the HI and the INI, and to handle the fact that there may be multiple interceptions of the same user by different LEAs.


CCContent of communication
HIHandover interface
INIInternal network interface
IRIIntercept related information
LEALaw enforcement agency
LEMFLaw enforcement management facility
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