Actually, I'm less worried about the voltage but the current limitations - I can just see someone hooking direct to a 110 v wall plug and trying to draw 5 or 10 amps thru the 24 gauge wire. I'm not sure that would be pretty, and a dead short should blow apart a splice or 2
You are exactly correct. The tel equipment is electrically (or electronically)designed to limit current to about 20ma using chokes and or capacitors. The equipment I use that operates at 110VAC has such limitations built in and a very sensitive relay on the receiving end that triggers upon approx 20ma.
Here is a few interesting posts I came across(things I didn't know).
"In the United States, the telephone company guarantees you no lower current than 20 mA or what is known to your phone company as a "long loop". A "short loop" will draw 50 to 70 mA, and an average loop, about 35 mA. Some countries will consider their maximum loop as low as 12 mA. In practice, United States telephones are usually capable of working at currents as low as 14 mA. "
"1 REN is the amount of AC current that's used by an old Bell type 2500 set with mechanical bells. The phone company has traditionally supplied about 5 REN from the CO - enough to ring 5 of the old fashioned phones. Since AC ringing current is limited at the CO, if you put 6 REN worth of phones on the line the ringing will either stop on all of the phones, one or more phones will sound very weak, or some phones will ring and some won't.
If you have a meter that will read AC current on a phone line (AC ma), you can use an old 2500 set, which uses 1 REN of current, to measure how much current it takes to ring the bell on that set on your meter. Once you know how many ma of current it takes for 1 REN, you'll be set to figure out how many REN a particular phone takes, or how many REN a phone line provides (before it stops ringing).
Using an analog port on a PBX in our office, we used the Network Meter™ to measure the current it took to ring an old AT&T 2500 set. It took 8.75ma AC. Then we measured the current it took to ring a Chinese phone we sell. It measured 8.26ma AC, but the phone said 1.4 REN on the label (if it was really 1.4 REN, it should have read 12.25ma AC). I guess I'll believe the meter, and figure that each of these phones is really a little less than 1 REN."
Also,anyone who applies ac wall power(unlimited source of energy with no such current restrictions) to a tel circuit gets just what they deserve.
