Telephone gadget required

[tigersaw]

Looking for a telephone gadget - something that will accept an incoming call, connect the call to an external 600 ohm audio source, then reset when the caller hangs up. (I want to make our automated weather system available to dial up as well as transmitting it on VHF).

Any techy ideas - what its called, where I can get one (uk approved)?

Originally Posted by tigersaw

Looking for a telephone gadget - something that will accept an incoming call, connect the call to an external 600 ohm audio source, then reset when the caller hangs up. (I want to make our automated weather system available to dial up as well as transmitting it on VHF).

Any techy ideas - what its called, where I can get one (uk approved)?

Low-tec solution: Just record it as an answer phone message!

[tigersaw]

Originally Posted by Kinvig

Low-tec solution: Just record it as an answer phone message!

It changes all the time, its an audio stream.
Found something in the end, some mystical black boxes for ?400

What connection is the audio device? (Also, surely this would be the destination for the incoming call, not the source? Anyhow...)

£400? I hope you're not the one paying the bills!!

The UK phone system (well, the PSTN one) works on 5v. IIRC, one pin carries the voltage, and it's a change in this voltage that makes the phone ring (if memory serves it drops to 3v to trigger ringing). The phone then breifly drops the connection (stops the positive feed connecting to the ground) to signify "I've picked up").

Then there's a pair of wires used in a duplex fashion for audio. That should be pretty simple to feed down a co-ax/3.5mm/etc etc connection.

Or have I misunderstood the OP?

[tigersaw]

The audio device has a 600 ohm balanced output. Whatever I use must be type approved, I can't twist wires and fudge about with safety related air traffic equipment.
I thought £400 was pretty good for a single box solution - the company supplies the BBC with similar kit, so they say.
PSTN uses -50 volt which when terminated drops to about 5V. The ringing cadence is at about 75 Volts.

Ah, I missed the uk approved comment in the OP.

Also, I've never had 75 volts out of a home PSTN line. Been a long while since I've played with PSTN, but I remember it being low voltage, the max I remember when the phone was "off-hook" was approx 10v. But anyway, that wasn't the point of the thread.

Since you need it to be approved, would it not be cheaper to get a 2nd hand X110P card & use a PC to output the audio?