The present document specifies a simple set of objectives, principles and responsibilities for the transmission performance of multiple interconnected networks that provide "traditional quality (POTS)" circuit switched telephony services.

The objectives, principles and responsibilities take account of the liberalization of telephony services and the interconnection of several separate networks, each with different topologies, in the provision of telephony connections.

The present document applies to:

• national and international networks;
• Digital Networks and Integrated Digital Networks (i.e. networks where the only analogue component may be the local loop).

The present document applies in the cases where the telephony service is:

• contracted between the network operator and the customer/end user; and
• contracted through a service provider.

It applies where:

• the caller pays for the call;
• the recipient pays for the call (e.g. the 800 service); or
• the cost of the call is shared by the caller and the recipient.

The present document does not apply to any segment of calls where either the calling or called terminal is a mobile "terminating network".