A GSM PLMN may be described by a limited set of access interfaces (refer to TS GSM 04.02 and 02.01) and a limited set of GSM PLMN connection types to support the telecommunication services described in the GSM 02-series of specifications. This specification identifies and defines these connection types in so far as they relate to the particular network capabilities for a GSM PLMN. The basic lower layer capabilities of a GSM PLMN are represented by a set of GSM PLMN connection types. The definition of a set of GSM PLMN connection types provides the necessary input to identify network capabilities of a GSM PLMN. In addition to describing network capabilities of a GSM PLMN, the identification of connection types facilitates the specification of network-to-network interfaces. It may also assist in the allocation of network performance parameters. This specification should be considered in conjunction with other GSM specifications with particular reference to TS GSM 01.02, 02.01, 02.02, 02.03, 03.01, 03.02, 04.02 and 04.03. This specification provides a bridge between the service specification in the GSM 02-series of specification and the more detailed specifications such as TS GSM of the 03, 04, 07 and 09 series. As such, it establishes a framework for the specification and understanding of the more detailed specifications. It is therefore not a specification against which detailed conformance testing can be performed. However, it shall be considered mandatory for the understanding of the more detailed specifications and used to resolve issues of conflict in these specifications.