> Date: Tue, 23 Feb 2016 19:06:44 -0500
> From: doug <dmcgarrett@xxxxxxxxxxxxx>
> To: phil@xxxxxxxxxxxxx, alsa-user@xxxxxxxxxxxxxxxxxxxxx
>
>
> On 02/23/2016 03:10 PM, Philip Rhoades wrote:
> > People,
> >
> > I know this is a bit of a long shot but does anyone here have any
> > experience setting up a voicemail recording system for a POTS phone? I
> > thought it should be simpler than using say using Asterisk to set up a
> > whole PABX but maybe it isn't . .
> >
> > Yhanks,
> >
> > Phil.
> It depends on what you are trying to do. If you just want to record the
> audio on a telephone line, the easiest way is
> a small audio transformer and a capacitor. Say a 10000 Ohm 1:1 audio
> transformer and about a 0.1 microfarad capacitor
> rated at 100 volts DC or better in series with the transformer on the
> phone line side. Connect the secondary to the recorder
> or computer line input.
>
> If you're trying to run voice in both directions from, say, a computer
> to the phone line, you need a telephone modem, which
> is explicitly designed to do that job.
If you use the transformer and capacitor solution, you'll also
need something to provide a DC path across the phone line or the
phone company switch will hang up the call. Here's a schematic I
posted to another forum:
https://tech.lds.org/forum/download/file.php?id=2636
If maximum economy is required, especially for a one-time event,
you can use a 1K resister instead of the choke and drop the MOV,
Zener diodes, and R1.
HTH
Robert
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