autoanswer telephone line

[merco]

hi
how is it possibile to wait for some rings and then activate the line
to capture DTMF signals ?
thank you

 

[OBones]

hi
how is it possibile to wait for some rings and then activate the line
to capture DTMF signals ?
thank you

Yes.

 

[merco]

well, i see...
but i asked "how" ?


OBones ha scritto:

 

[OBones]

well, i see...
but i asked "how" ?

I know, hence why I canceled the message, I missed the "how" part.

Detecting rings is done with a RC network across the line, like on this
schematic with R7/C3 (bottom right)

http://obones.com/2Lignes1Tel/Schema.png

On this one, you get an optocoupler in the path to interface with low
level voltage (12V) logic.

To activate the line, I think it's enough to put a resistor across it
but can't remember the exact value. And detecting DTMF tones can be done
with an MT8870 like on this schematic:

http://obones.com/2Lignes1Tel/ToneCommand2#/Schema.png

Hope this helps.

 

[merco]

thanks, the problem i have is how to pick up the line...
maybe a 600 ohm resistor ?

 

[John Fields]

thanks, the problem i have is how to pick up the line...
maybe a 600 ohm resistor ?

---
Yes, that will work.

The second problem is that you're top posting. Please bottom post.

Thanks,

 

[Joe G \(Home\)]

You need several circuits.

a. Ring detect circuit

b. Something to count the rings before answer

c. something to loop line and draw loop current from line/telephone exchange

d. something to couple the audio after looping

e. something to decode the dtmf

f. something to hangup.

JG

 

[Nico Coesel]

hi
how is it possibile to wait for some rings and then activate the line
to capture DTMF signals ?
thank you

By using a ring detector, a DTMF receiver and a microcontroller.

 

[Michael Black]

hi
how is it possibile to wait for some rings and then activate the line
to capture DTMF signals ?
thank you

You mean an "infinity bug"?

Michael

 

[Rich Grise]

hi
how is it possibile to wait for some rings and then activate the line
to capture DTMF signals ?
thank you

Hack an ordinary answering machine?

Good Luck!
Rich

 

[jasen]

hi
how is it possibile to wait for some rings and then activate the line
to capture DTMF signals ?
thank you

a ring detector, monostable, counter, relay, line transfromer,
DTMF decoder...

or use a modem. many V90 modems will decode DTMF if you ask them nicely.

Bye.
Jasen