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Wireless phone busy indicator

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grrr_arrghh

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Hi.

I have an answer service (BT CallMinder, similar to BT-1571 for those in the UK who may have heard of it) that gives a pulsed dialling tone when you have messages waiting for you.

I would like some kind of device that would tell me if the phone was in use, not in use but with messages waiting, or not in use and with no messages waiting. In itself it shouldn’t be too difficult, as there are many fairly basic circuits on the net that give busy/not busy indicators. I also image that a circuit to measure whether the tone is pulsed or not should be quite easy to make, as I can know what the frequency of the pulse is.

1) However, my first problem is: If my device is connected to the phone line, to measure the dialling tone, won’t this emulate a phone that is ‘off the hook’, thus stopping anyone from being able to phone me?

2) My second problem is that I would like to situate the device somewhere where I don’t have access to a phone line. I would need some way of sending the signal wirelessly (it would only need to have three states) to the receiver unit. What is the best way to go about doing this? (in your personal opinion). A computer could be used as the receiver, if this was easiest.

Answers to the above questions would be greatly appreciated, and when answering the above questions, please ignore the questions below, as I may not use the ideas below, and they make it considerably more complicated.

I am also considering going a bit further (why settle for half?)

3) I believe that BT will turn on ‘call waiting’ for free, all you need is a device to tell you whether you have a call waiting or not. Would this be easy to integrate into my system?

4) I have heard that when you receive a call, the sender’s number is sent along with the call, and I have seen phones that can display this. How difficult would it be to decode this signal, and integrate this into my system?


If I didn’t use the idea in question 4, this could all be displayed on LEDs, however if I did use number 4, I guess it would have to using 7-seg displays/LCD displays, or it could possibly be fed into a computer, if that was easier (I have NO knowledge of programming).

Thanks for any ideas - they will all be helpful.

Tim
 
some one must be able to give me some ideas as to where to start, at least...

maybe somene could point out how to make the sender/reciever part, I could probably work out the rest.

Thanks

Tim
 
grrr_arrghh said:
some one must be able to give me some ideas as to where to start, at least...

Touching the phone system is seriously frowned upon in the UK, which is why there has never been any phone projects in UK magazines. Any device connected to the UK phone network has to pass strict, and expensive, approval testing - so generally people don't mess with it, or if they do they keep quiet about it!.

maybe somene could point out how to make the sender/reciever part, I could probably work out the rest.

You could use licence free radio modules, if you need three states you can send encoded data - either use a PIC, or specific encoder/decoder chips - Holtek make them, available from Maplin in the UK.
 
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