Question about modems

[Fred Cisin]

> A "telephone line simulator".

On Wed, 13 Nov 2019, Electronics Plus wrote:
> A young gent (about 22 yrs old) reminded me of HyperTerminal on XP. Since I
> have stacks of old working XP laptops, I can simply connect 2 modems to each
> other via a POTS phone cable, attach each modem via serial cable to a
> different laptop, and set one to Listen and the other to Answer via
> HyperTerminal. If I want to transfer files, I could use PuTTy, which also
> runs on XP. Seems like that should take care of both send and receive on
> both modems? Now to make a simple batch file that can automate the process,
> since I don't want to do everything manually for 50+ modems!
>
> I only have 2 acoustic modems, so I will set them aside for now. I used to
> have a "telephone tester" machine from Radio Shack, but it disappeared many
> years ago. I do have an old TAB book of "telephone projects" and another for
> test equipment that I could build, but that would be a lot of trouble to
> only test about 50 items.

Not enough to justify investing in specialized test gear.  OTOH, you can 
have fun with it.   Small children seem to enjoy having "toy phones" that 
actually work, etc.   When I was teaching my dog to tell me when the phone 
rang, I had a button in my pocket, . . .

Testing DTMF tones, etc. is more involved, but if you hear it attempting 
to "dial", that's probably close enough.
"Dial tone" is a little more involved, and a thorough test should include 
whether it detects it properly, etc.
Going "off hook" on an incoming call requires creating a ring signal 
(90VAC at 20 Hz), . . .

But, being up-front with your customers about the extent of the testing 
means no ill will if not all functions and capabilities are tested.