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.