The present document provides basic interception requirements within a Third Generation Mobile Communication System (3GMS). The specification describes the service requirements from a Law Enforcement point of view only. The aim of this document is to define a 3GMS interception system that supports a number of regional interception regulations@ but these regulations are not repeated here as they vary. Regional interception requirements shall rely on this specification to derive such information as they require. These interception requirements shall be used to derive specific network requirements.