Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site gc49.UUCP Path: utzoo!watmath!clyde!burl!gc49!smithrd From: smithrd@gc49.UUCP (Randy D. Smith) Newsgroups: net.dcom Subject: Re: Phone line blues Message-ID: <229@gc49.UUCP> Date: Wed, 5-Mar-86 13:07:13 EST Article-I.D.: gc49.229 Posted: Wed Mar 5 13:07:13 1986 Date-Received: Fri, 7-Mar-86 04:32:42 EST References: <223@iuvax.UUCP> Reply-To: smithrd@gc49.UUCP (Randy D. Smith) Distribution: net Organization: AT&T Technologies, Guilford Center, NC Lines: 59 In article <223@iuvax.UUCP> mosier@iuvax.UUCP (Steve Mosier) writes: >In September, the local phone company (Indiana Bell) changed over to a >digital switching system. Since that time, trying to use a modem has >met with less than desirable results... >...He finally concluded that the "lines were >out of phase" His efforts to correct the problems seems to have >succeeded, somewhat. However, the preformance is far from what it was >previous to the switch over. The phone people seem to take the attitude >that "if you can hear and talk to the other person, everything is ok"... Do you have voice grade lines? Or data lines?? I expect that each is fully specified, and that the phone company there should know how to ensure that the specs are met. If you are dealing with voice grade lines, then they're probably "balanced" lines. They work for voice, and the circuitry that makes them "balanced" adds to the line's quality as a voice line. Data lines are USUALLY unbalanced; that circuitry that makes the line balanced, and improves the quality of the voice line, introduces the phase differences that interferes with the line's usefulness for data transfer. >...Our resident engineer maintains that, although you can hear and talk, >the lines are probably much out of spec since a modem that is designed to >operate over a voice grade line simply can't. I've called the phone co >several times now, with no results... >-steve mosier@indiana.csnet or {cbosgd,ihnp4,seismo}!iuvax!mosie When faced with deciding whether an operating companies lines are "out of spec" or whether a manufacturer has designed for "normal operating conditions", I'd probably assume the latter. People have used voice lines for data for a long time, and don't think anything about it until it stops working. Then they find out that there is no guarantee, unless they spring for the data line. I ran into an equally frustrating experience a couple of years ago. After a year of error free communication between the CA bay area and NJ, I moved back to NJ within 5 miles of the computer I was talking to, and with the move, I lost my ability to communicate with the machine. Five miles, versus 3000, and in the heart of "phone company land"! (Actually, NJ is owned by Prudential; AT&T just leases it :-) ) I had a data line installed, with no improvement. Fortunately, after a couple of months of frustration, the union workers went on strike, and the operating companies had to send engineers out for simple requests like mine. The engineer who worked on my line said it was one of the strangest things, but that he could get it to work. He said he had to run a balanced line from the central office to a point about half way to my location, then run an unbalanced line the rest of the way. All I knew was that it worked (until the first thunderstorm, but that's another story). Note: I work for AT&T, but I definitely don't represent "the phone company". I'm posting only to add a little light to the subject. I post from the perspective of someone who has run into similar problems. I'm a software-type, not hardware, so take it easy on my (perhaps incorrect) usage of terminology. -- Randy D. Smith (919) 279-5312 AT&T Technologies, Guilford Center, NC ....!{ihnp4,burl}!{gc49,gc3ba}!smithrd