DTMF

Dual-tone multifrequency: The paired, high- and low-frequency tones that make up touch-tone dialing.

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C21 Communications provides solutions and products designed to reduce the cost of telephony for SoHo and SME businesses, right through to global enterprises.

C21 Communications Ltd. Harwell International Business Centre, 173 Curie Avenue, Harwell, Didcot, Oxfordshire, OX11 0QG.

Enquiries:

Contact Number: +44 1235 838592