The CCITT, considering that the I-series of Recommendations apply to the general concept and to the network capabilities of an ISDN. Specifically, Recommendations I.210, I.211 and I.212 describe, in a general way, the principles of telecommunication services, the bearer services and the teleservices supported by an ISDN; that the F-series of Recommendations describe the operations and quality of Telematic services; that many countries wish to adopt a common strategy for introducing the non-voice Telematic services on ISDN.