The first DTMF sound producing phones were introduces by Bell Systems. Rotating phones interrupted electric connections when they turned, which resulted in electric pulses that were produced and were read as commandos.
The first versions of phone signalling were pulse calls. Signaling systems have been developed to fill that need – both in regard to routing and calling, as well as integrating with a telephony system. Similarly to how long we’ve had access to the telegraph and telephony in whole, we’ve needed ways to interact with systems in a mechanical way.
DTMF technique isn’t interruption sensitive and is considered reliable.The US based company Bell Labs invented the technique.DTMF is a way to send information over vast distances.Many that grew up in the 1970s or earlier are used to phones with rotary dials which were much more ineffective to call with. The system has also proved reliability.ĭTMF came to the US in the 1940s as a streamline of a system for telephony that then was built on the impulse system, with a rotary dial. Number 1 consists of the tones 6 Hz for example. Every click sends two tones on two different frequencies.Every number have their own, predestined frequencies. The tones you hear when pressing buttons on a phone, it DTMF. The prestigious American company Bell Labs that is owned by Nokia is the developer of DTMF. This can be a code that is used to send information with radio och phone. The abbreviation DTMF stands for Dual Tone Multiple-Frequency, also called Touch Tone.
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