Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!sun!sun-barr!texsun!texbell!vector!telecom-gateway From: jeff@tc.fluke.com (Jeff Stearns) Newsgroups: comp.dcom.telecom Subject: Re: regular noise/interference over long distance credit card calls Message-ID: Date: 19 May 89 00:41:08 GMT Sender: news@vector.Dallas.TX.US Organization: John Fluke Mfg. Co., Inc., Everett, WA Lines: 28 Approved: telecom-request@vector.dallas.tx.us X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@vector.dallas.tx.us X-TELECOM-Digest: volume 9, issue 169, message 6 of 8 In article Steve Dyer writes: > I was travelling on business last month and attepted to use my trusty Toshiba > laptop which comes with a 1200 baud modem... Whenever I dialed direct with > the credit card, I would end up getting an incredibly regular noise pattern: > what seemed like { once a >second--you could set your watch with it... Steve, Most phone calls are transmitted as a stream of digital data. (Odd, ain't it; the modem converts digital to analog so the central office can convert it back to digital for transmission...) This digital data stream passes from one network switch to another. The network switches probably aren't synchronized to the same clock. One switch is running slightly faster than the other; thus the digital data stream is constantly and steadily "slipping" as it passes from one to the other. The scrambled bit pattern often contains characters ~ or } or DEL (they're rich in 1-bits). A quick workaround? Route the call along a different path. Using a different LD carrier is very likely to accomplish this. -- Jeff Stearns John Fluke Mfg. Co, Inc. (206) 356-5064 jeff@tc.fluke.COM {uw-beaver,microsoft,sun}!fluke!jeff PS - Calling all users of the Vitalink TransLAN IV Ethernet bridge! Please drop me a line.