ETSI TS 101 671 is step 3 of a three-step approach to describe a generic Handover Interface (HI) for the provision of lawful interception from a Network Operator, an Access Provider or a Service Provider (NWO/AP/SvP) to the Law Enforcement Agencies (LEAs). The provision of lawful interception is a requirement of national law, which is usually mandatory for the operation of any telecommunication service.

Step 1 contains the requirements for lawful interception from a users (LEAs) point of view and is published in ETSI TS 101 331 [1].

Step 2 describes the derived network functions and the general architecture (or functional model) and is published in ETSI ES 201 158 [2].

The present document specifies:

• the generic flow of information as well as the procedures and information elements, which are applicable to any future telecommunication network or service;
• the network/service specific protocols relating to the provision of lawful interception at the Handover Interface (HI), for the following networks/services:
  • switched circuit; and
  • packet data.

The technologies covered in the present document are: GSM, TETRA, GPRS, ISDN, PSTN, fixed NGN (including PSTN/ISDN emulation) and fixed IMS PSTN simulation.

New telecommunication networks and services are IP based Packet Switched networks and Packet Switched services . Some legacy networks and services are still Circuit Switched networks and/or services even if the transport might be IP based. For new LI implementations it is therefore recommended to use the ETSI TS 102 232 series (part 1 to 7) [i.6] instead of the present document. Current implementations of the present document are advised to migrate to the ETSI TS 102 232 series [i.6].

NOTE: The HI3 transport technology change may have an impact on the delivery network between the CSP and the LEA. The ETSI TS 102 232 series [i.6], 3GPP TS 33.107 [71] and 3GPP TS 33.108 [61] make use of imports from the present document. Taking the current IP based networks and services into account, these imports from circuit switched specifications seem not to be appropriate anymore. These imports will therefore be removed. After these imports are made obsolete in these specifications, the present document will be made "historical" according to the ETSI Directive. This does not exclude local regulations continuing to require the use of ETSI TS 101 671. The imports from the present document can be made obsolete by updating ETSI TS 103 280 [i.7] and redirecting the imports to ETSI TS 103 280 [i.7]. In the ETSI TC LI plenary meeting #29 in Dun Laoghaire, January 2012 it was decided not to upgrade the the present document anymore to ETSI ES 201 671 [i.5].