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Q Basics of Tele-Communication Stroger Switching System Crossbar Switching Space Division Switching Time Division Switching ISDN Help Exit

Q Basics of Tele-Communication Stroger Switching System Crossbar Switching Space Division Switching Time Division Switching ISDN Help Exit

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Touch Tonę Dialling

In a rotary dial telephone, it takes about 12 seconds to dial a 7-digit number, whereas step-by-step switching does not respond to rates higher than 10-12 pulses per second. From subscriber point of view faster dialing ratę was needed, and to accomplish it Touch tonę dialing phones were introduced first in 1964.

Touch Tonę dialing phones have push button keypad in which “Pushing” a button generate a ‘tonę’ which is a combination of two frequencies, one from the lower band and other from the upper band.When a key is press, the lower and upper frequencies for that key are sent out over the phone linę to the phone company's switching equipment, which converts the tones back into the proper digits with the help of decoder.