The establishment in various countries of message handling service in association with public networks creates the need to produce Recommendations covering the aspects of public message handling services.
ITU-T F.421-1993 Referenced Document
ITU-T F.421 MESSAGE HANDLING SERVICES: INTERCOMMUNICATION BETWEEN THE IPM SERVICE AND THE TELEX SERVICE
ITU-T F.421-1993 history
1993ITU-T F.421-1993 MESSAGE HANDLING SERVICES: INTERCOMMUNICATION BETWEEN THE IPM SERVICE AND THE TELEX SERVICE
1988ITU-T F.421-1988 Message handling services: Intercommunication between the IPM service and the telex service