msa@rwing.uucp (Mark Anacker) (09/02/89)
Hi out there in telecom land... I have a situation here, and I was wondering if anyone out there in this group has any advice. Some friends live in a rural (*really rural*) area of the state (WA). Their phone service is party line, with 3 or 4 others on the line. Instead of the old system of "1 long, 2 short" rings or whatever, the telco sends the rings signal at different frequencies for each party. Thus my friends' ring is 50Hz, instead of the usual 20Hz. They then had to buy a small box that goes inline with their incoming line and beeps when a ring signal of the appropriate frequency comes along. A side effect of this is that the ring signal is not passed through the box at all, making it kind of hard to hook up an answering machine or modem (or anything). Also, since the only audible indicator is in the filter box, you can't hear the phone ring outside that room. What I had in mind was to modify one of these filter boxes so that instead of beeping on a 50Hz ring, it would close a relay and bridge the house side of the line onto the incoming side. This would then allow the ring signal to get to the rest of the house. We've verified that their phones and stuff will recognize a 50Hz ring (also all other rings)., so they should work. I'd like to know if anybody out there has done anything like this already. I know this look like a sci.electronics posting, but it's really telcomm specific. Besides, Patrick seems to know everything about the system anyway :-) Sorry for the length. Thanks for any help.
bobf@uunet.uu.net (BFrankston) (09/03/89)
Modem on a party line? Check the laws. I think it is illegal to have a modem on a party line since the other parties must be allowed to break in for emergency calls. Full name: Bob Frankston
john@zygot.ati.com (John Higdon) (09/04/89)
In article <telecom-v09i0343m02@vector.dallas.tx.us>, msa@rwing.uucp (Mark Anacker) writes: > I have a situation here, and I was wondering if anyone out there in this > group has any advice. Some friends live in a rural (*really rural*) area of > the state (WA). Their phone service is party line, with 3 or 4 others on > the line. Instead of the old system of "1 long, 2 short" rings or whatever, > the telco sends the rings signal at different frequencies for each party. > Thus my friends' ring is 50Hz, instead of the usual 20Hz. They then had to > buy a small box that goes inline with their incoming line and beeps when a > ring signal of the appropriate frequency comes along. A side effect of this > is that the ring signal is not passed through the box at all, making it > kind of hard to hook up an answering machine or modem (or anything). Most of your IC cookbooks have filter circuits that would be suitable for bandpassing the fifty hertz ring signal that you could then use to drive a simple detector circuit. But, there is a major caveat here. It is not legal for you to do this. With all of the hoopla about CPE and divestature, and "doing your own thing", some people were left out in the cold. FCC registration ONLY applies to equipment to be installed on non-coin, one-party lines. For obvious reasons, party lines are exempt from all of the deregulation. For instance, even though your proposal would prevent the answering machine from picking up your party line neighbor's calls, on most party lines this would not be the case. I know of no answering maching that can be taught to pick up "one long and two short". The other problem would occur when you had some type of automatic dialer that would not know if the line was already in use (or be able to relinquish it in case of an emergency.) And remember, failure of your CPE not only puts your service out of order, but all those on the party line as well. (This is the main reason for the regulation.) Being a hacker myself, I know that a simple matter like regulations isn't going to stop your scientific endeavors, but you should be extremely careful about what you put on that party line. If someone dies because help couldn't be summoned due to some gadget of yours, you might find yourself in deep doo-doo. -- John Higdon | P. O. Box 7648 | +1 408 723 1395 john@zygot.ati.com | San Jose, CA 95150 | M o o !
smb@hector.att.com (09/04/89)
What you propose is almost certainly against FCC regs. The general rule these days that you can hook any legal phone up yourself does not apply to party lines.