Strange high pitch pulsing noise via FXO (TDM400)

[Lightman]

Hi

I'm having a strange high pitch, pulsing noise, about 200ms long, 1khz, it repeats randomly every 1 to 6 seconds, I only heard it when I'm going through the FXO port of the digium TDM400.

it's not the phone line, I try using it with the SPA3000 and works fine.
SIP phone to sip phone sounds ok, voicemail too, but when I use FXO i get this annoying sound.

another thing I noted was that 50% of the times, PSTN provider doesn't understand what I dial, It seems that the same noise is going out to the PSTN as well and make it difficult to decode the tones.

again tested with SPA3000 and regular POTs phones and no problem with the line.

could it be the computer?, I have exactly the same software setup in another server (different hardware) and works perfectly.

I'm using centos 4.5 , asterisk 1.4.1
hardware is: ASUS K8V-MX (Via K8M800), Sempron 3000 skt 754, 512MB DDR400 kingston, Digium TDM400 card with 2 FXO boards and 2 RTL 8139 NIC cards and IDE hd.

any ideas, help, could it be the NIC cards interfering with the interrupts of the TDM card?, I'm LOST, i don't think that it's a software problem because exactly the same versions and basic configurations I have them working on a different machine, the difference is hardware.
the machine that works has 1 NIC RTL8139, 1 onboard gigabit lan, intel D945GCNL with intel E2140 and 1GB ddr2 533, sata HD.

thanks
c-u
Light

[Valer77]

There are few commercial solutions that can help you. You should look for software for noise reduction in VoIP. Some of these solutions work very well with Asterisk. There are both integrated solutions and external solutions that do not require any compilation.

[Lightman]

Originally Posted by Valer77

There are few commercial solutions that can help you. You should look for software for noise reduction in VoIP. Some of these solutions work very well with Asterisk. There are both integrated solutions and external solutions that do not require any compilation.

Hello valer77 thanks for take the time to reply

The problem was solved by changing the motherboard to nForce2, it seems that VIA doesn't handle interrupt very well, a software solution will not fix the problem since the noise is generated by the hardware loosing sync during the dma transfer.

I talked to the guys at digium and they never heard of anything like my problem ouch... luckily changing to nForce motherboard fixes the problem and it's been working perfectly for the last 8 or more months

Still a software noise reduction is a interesting add-on for asterisk, there are some applications that i could use it, thanks for the info.

c-u
Light