Overview
On 4th August 1998 the European Council Decision regarding the
CTR 21 has been published in the Official Journal of the EC. The CTR
21 applies to all non voice terminal equipment with DTMF-dialling
which is intended to be connected to the analogue PSTN (Public
Switched Telephone Network).
CTR 21 (Common Technical Regulation) for the attachment
requirements for connection to the analogue public switched
telephone networks of terminal equipment (excluding terminal
equipment supporting the voice telephony justified case service)
in which network addressing, if provided, is by means of dual tone
multifrequency signalling.