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New Member

Bad Static on FXO port

I have a 2811 running CME with a VIC-2FXO card installed. My code version is 12.4(4)T I have a pots line connected to the FXO card for incoming and outgoing calls, and a couple of 7960 phones. Everything works except that I have very very bad static (cracking) on all incoming and outgoing calls. I have turned vad on/off, comfort noise on/off, I have played with input gain, output gain, and impedence settings to no avail. I know it is not the pots line because I can connect a phone to the line and I get no noise at all. When making a call as soon as the call is connected the static starts (when the diplay on the phone says "Connected" the static starts.) Any ideas? This is my first posting here so if there is more info that is standard to put in that I haven't I apologize. I have googled and searched here at Cisco to try to find a solution and have found practically nothing. I have connected the phones to 4ESW card with inline power, and connected them to a 2924 using power bricks, and both are just as bad. I don't know what to try next. Any help would be appreciated.

Scott

5 REPLIES

Re: Bad Static on FXO port

Happens on every call?

Try doing the THL tone sweep in the following document to see what the best match impedance setting is and set the impedance to that (and maybe others) and see if adjusting impedance helps any.

http://www.cisco.com/en/US/tech/tk652/tk701/technologies_tech_note09186a0080477a06.shtml#thl

New Member

Re: Bad Static on FXO port

Thanks for the reply!!

I ran the test and it came back with complex5, which I then configured. Didn't make any difference. Setting the input gain to -6 is like turning down the volume, but the static is still really bad, and the volume is so low you can't hear the person at the end of the line. Could I have bad hardware? Also the cable for the post line from the demarc to the router is cat5 and is about 20 feet long. Could this be the problem?

Scott

Re: Bad Static on FXO port

Why is it -6? Usually you shouldn't have to lower it, try the default but that isn't going to solve the static problems probably.

How far are you from the CO? What part of the country?

rural area?

Try using a regular old 2 wire phone line into FXO port. These are touchy about cabling at times and phone lines being used.

Others on this forum and elsewhere, have used DSL filters on phone lines to clear up issues like this and it fixed things up. I know it is out there, but may be worth trying also if you have one handy.

New Member

Re: Bad Static on FXO port

I tried running regular telephone wiring, with the same results.

I found some references to changing the input and output gain could reduce or eliminated the static, but that didn't work.

I am pretty far from the CO, about 22,000 feet (Tried getting dsl but no luck!) I'll dig up a dsl filter and see if that helps.

Thanks!

Scott

New Member

Re: Bad Static on FXO port

Sorry to tell you this I have been working on CME since the ITS days and it is not where it needs to be yet. I have it at a customer site having the same issues and same configuration except I have a inline switch module in the 2811 with 8 ports. I replaced the FXO card and the PVMD2 -16 thinking it might be the DSP resources. I have spent hours tweaking the input gain and output attenation. So I called TAC two days of troublshooting and now Cisco wants me to replace the whole chassis and everything inside. The customer is ready to kill me over 5 phone site.

PS There is a light at the end of the tunnel. Watch the Voice Con John Chambers WEB Cast on 3/8 and alot will be explained about product offerings. Since I am under NDA as a Gold Cisco Partner I can not go into details.

Hang in there I have been working on IPT and VoIP since 1998 and let me tell you this it is 1000 times better than it was then.Before that I spent 8 years working on Nortel, NEC PBX's and KSU's Cisco has the lead on the other players and is steadly pulling away.

Sorry I could not help you and went off on a tangent, but post the solution if you find one and I will let you know if the chassis replacment fixes mine.

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