wrote:
On Sun, 27 Aug 2017 00:15:39 +0700, JJ wrote:

On Sat, 26 Aug 2017 01:39:06 -0400, wrote:
I have a dual core XP machine and my dial up connection stopped
working. I have tried 3 different Win Modems. The modems install OK
and the diagnostics say it is connecting OK but when I try dialing
out, I get the message that there is no dial tone. That phone wire
works in a phone (same wire that plugs into the modem) I can also plug
a phone into the other port on the modem and dial out through it. I
tried swapping ports to be sure it wasn't just labeled wrong.
There is no activity on the line when I listen from another phone.
Any ideas?
If I'm not mistaken, land line telephone system has more than one standard.
Similar like TV signal standards e.g. NTSC-only or PAL-only on old TVs,
except that most TV nowadays support both standards. Or 110V vs 220V power
source standard in countries. Phones/faxes/modems only support one standard,
AFAIK. If this is the case, perhaps your modems aren't built for the phone
system used in your country.

This is all USA stuff made for POTS phone lines.

I don't recollect any Hayes AT command set items that
control the electrical standard. I would expect when you
buy a product, it's designed for the country you are in.
(A US purchase for US POTS standards.)

I'm trying to remember now, how I debugged my dialup modem.
I recollect I was able to snag all the AT commands that
were sent to it.

Looking through some old messages, I was using "portmon".

https://docs.microsoft.com/en-us/sys...nloads/portmon

But since you're not getting dial tone, I don't think
the dialing string makes any difference to that.

Paul