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???
06/16/05 21:05
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#95122 - Unlikely to work
Responding to: ???'s previous message
Reza Javan said:
It is my final year project ... signalling after connection with pulse

It is very unlikely that this will work reliably.

As this is your final year, you should have come across the terms "in-band" and "out-of-band" in terms of telephone signalling?

Basically, "in-band" means that the signalling is carried in the same "channel" as the payload - in voice telephony terms, that means that the signalling will be audible in the other party's earpiece.
DTMF and call-progress tones such as Dial Tone and Busy (Engaged) Tone are examples of "in-band" signalling.

"out-of-band" means that the signalling is not carried in the same "channel" as the payload - in voice telephony terms, that means that the signalling will not be audible in the other party's earpiece.
Pulse (or "Loop-Disconnect") dialling is an example of "out-of-band" signalling: the signalling takes place between the phone and its local exchange - it is not transported across the network to the called party!
(ISDN uses "out-of-band" signalling: it has a separate channel - the D-Channel - for signalling)

Clearly, for your project to work over a standard analogue telephone line, you must use in-band signalling.

Yes, in some circumstances, it may be possible to hear some clicks due to pulse dialling from the other phone, but you should certainly not design a system that relies upon this!

DTMF has been specifically designed for this purpose - use it!


List of 16 messages in thread
TopicAuthorDate
Pulse Detection            01/01/70 00:00      
   Discussed here            01/01/70 00:00      
      I'll check it            01/01/70 00:00      
         Detect where?            01/01/70 00:00      
         pulse detection            01/01/70 00:00      
            I doubt it.            01/01/70 00:00      
               Re: I doubt it            01/01/70 00:00      
         Unlikely to work            01/01/70 00:00      
      First MicroController Project            01/01/70 00:00      
         Look over here,,,,            01/01/70 00:00      
            Cliche            01/01/70 00:00      
   But if there is no way...            01/01/70 00:00      
      tricky            01/01/70 00:00      
         Last Speech!            01/01/70 00:00      
      Thanks            01/01/70 00:00      
   Thanks            01/01/70 00:00      

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