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 multi-frequency signalling.