INTERNATIONAL TELECOMMUNICATION UNION ITU-T RECOMMENDATION SUMMARY Rec. No. : F.73 Title : Operational principles for communication between terminals of the international telex service and data terminal equipment on packet switched public data networks Study Group : I - Services Version : Revised Date of adoption : 1990 Notes : Corrigendum 12/90 The procedures defined in Recommendation F.73 enable telex subscribers to communicate with both packet mode and character mode data terminal equipment (DTE) connected to the PSPDN directly or via other networks. In the reverse direction, the provisions of Recommendation F.73 enable users of packet mode and character mode DTEs, connected to a PSPDN directly or via other networks, to communicate with telex subscribers. Recommendation F.73 applies to user classes 8-13 and 20-23 as defined in Recommendation X.1. Categories of access for DTEs accessing the PSPDN are shown in Recommendation X.10. Recommendation F.73 does not apply to other Telematic services that may be supported by packet switched public data networks and interworking with the telex service. For example, interworking between the telex service and the teletex service or the interpersonal messaging service is not within the scope of Recommendation F.73. Such interworking scenarios are defined in other Recommendations. Call establishment from a telex terminal via a PSPDN to a character-mode DTE connected to the public switched telephone network (PSTN) requires further study. Recommendation F.73 defines an interworking model and sets out the principles applicable to call set-up procedures and to the text transfer phase. To order the complete text of this Recommendation, please use the Order Form for ITU-T Recommendations. An electronic version of this form is available on ITUDOC (Winword: UPI=ITU-5265; ASCII: UPI=ITU-2488).