Check this out (I'm always the last to want to blame the hardware, so this amazes me): -----Original Message----- From: pmok [mailto:***@cisco.com] Sent: Thursday, May 03, 2001 6:03 PM To: j******@netsworkinc.com Subject: Case B385165 - 1750: as soon as pick up phone get loud screaching noise before dialing Hello Jason, according to the information you sent in, SJC has a chassis serial number of JAB044431DX and BFL has a chassis serial number of JAB044431DM. It is as I suspected: these two routers are from a bad manufacturing batch -- the PLL circuitry on the motherboard cannot lock the frequency as required and will not provide a stable clock output. The PLL will generate jitters causing noise or distortion on voice calls. The worst case is that the PLL will provide no clock output resulting in total failure to dial out (no dial tone). The way to recognize such units is via their chassis serial number: This problem will most likely be seen on units manufactured between datecode 0435 and 0448. It maybe seen on units prior to this datecode but this is unlikely. Here is how to decode the Chassis System serial #'s. The serial # has the datecode built into it. The format is LLLYYWWSSSS LLL=Location unit was built at. This would be JAB, JMX, or JEU YY =Year. This is from when we started the new serial # system (1997=01, 1998=02, 1999=03, 2000=04, 2001=05). WW= Work Week. This is the week of the year that the system was built. SSSS= Serial #. The Chassis Serial Number is located on the back panel of the router. This manufacturing defect is catastrophic -- if you attach an analog phone to an FXS port on the router and then pick up the phone and hear a good dialtone, your chassis is OK. If you have FXO ports, you can hook up the port to the PSTN wall-jack, dial-in over the PSTN, and the router will answer and return dialtone. Again, if the dialtone sounds good your chassis is not affected by this defect. I will have to submit an RMA order to ship you replacement 1750s new from the manufacturing plant. Please send me shipping information and a contact name and phone number at the address. I will make the arrangements and someone from the depot will be in contact to let you know when the replacement chassis should arrive. Please advise, thanks. Peng Mok (***@cisco.com, 919-392-****) > SJC is the hub for this FR network. All sites have the same gear. BFL & > SJC have a loud hissing noise even plugging a POTS phone right off the FXS > port. They get this before dialing, and it continues during the whole call > to the point that they can't hear anything. If they call SLO or OAK, the > remote sides can't hear it or tell there is a problem. SLO & OAK do not > have any problems calling between themselves or even detected problems on > their end when they call BFL or SJC. > > What could be affecting this? I've tweaked the settings today (5/3) to kill > all possible VAD/white noise possible, and still the same for those two > sites. Sound like bad hardware? I've also included the configs prior to > this (4/10), which the customer can't tell the difference between. > -- Jason Roysdon, CCNP+Security/CCDP, MCSE, CNA, Network+, A+ List email: [EMAIL PROTECTED] Homepage: http://jason.artoo.net/ Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=3127&t=3127 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
