Recommendation F.200 lays down the provisions for the operation of the automatic international Teletex service. In particular, Recommendation F.200 defines the basic service requirements and principles for interworking between Teletex and telex services via a conversion facility (CF).

Recommendation T.60 defines the requirements for terminal equipment used in the international Teletex service, including the interworking with telex terminals, and the conversion table to the telex repertoire in case of interworking.

Recommendation T.61 defines the character repertoire and the coded character sets for the Teletex service.

Recommendation T.62 defines the end-to-end control procedures to be used within the Teletex service as well as between a Teletex terminal and a Teletex/telex conversion facility (CF).

Recommendation T.70 defines the network-independent basic transport service applicable to Teletex terminals, as well as between a Teletex terminal and a CF.

This Recommendation defines the requirements additional to Recommendation T.62 for use between a Teletex terminal and a CF to provide interworking between Teletex and telex services, using store-and-forward principles, in the following cases:

a) when the CF and Teletex terminal are in the same country, with message transfer in either direction;

b) when the CF and Teletex terminal are in different countries, with message transfer in the CF to Teletex terminal direction. This is subject to bilateral agreement.

Note 1 – Due to practical operational difficulties such as charging, message transfer in the direction from a Teletex terminal to a CF in another country is not considered in this Recommendation.

Note 2 – The requirements of interconnection of CFs for the international interworking between Teletex and telex services are for further study.

Note 3 – The real-time conversion operation is not considered in this Recommendation.

The provisions in this Recommendation are independent of the means and procedures for communication between the CF and the telex network. These are covered in Recommendation F.200.