PBX (or something) for modem testing

Ethan Dicks ethan.dicks at gmail.com
Wed Dec 4 11:40:43 CST 2019

On Wed, Dec 4, 2019 at 12:26 AM Glen Slick via cctalk
<cctalk at classiccmp.org> wrote:
> When I worked in a group that was doing modem related software over 20
> years ago two of the telephone line simulators we used were from
> Teltone and from TAS.
> You can find Teltone TLS-2, 3, 4, and 5 boxes on eBay. The TLS-2 and
> TLS-3 are two line boxes, the TLS-4 and TLS-5 are four line boxes.

I have a TLS-4 box.  It's handy.  We got it because we were developing
our own TelCo simulator, 2 line, but you could dial different numbers
to simulate different connection failure conditions (busy, fast busy,
half-connect...)  We did end up shipping our own box but it wasn't a
big seller.  It was fantastic to have around, though, when I was
writing autodialer software for our product and I needed to simulate
different external events on demand to test error reporting and

I can definitely recommend the TLS products for a small setup.


P.S. - I know where my TLS-4 is and this thread reminds me I need to
find the manual for it.  I could bring it and some other gear to a
Vintage Computer Fest for a display that's centered around serial
comms and dialup.

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