radio interference on PTSN Calls

Unanswered Question
May 7th, 2007

I have 3 POTS Lines connected to my MGCP Gateway. When I call in and out you can hear a radio station that is a couple of blocks down the road. Unfortunately it is a crappy Talk Radio Station otherwise we might live with it:) Since the interference is coming from outside our customer premise punchblock there is not much I can do like use shielded cable which is what I normally would try in situations similar to this in environments that I can control. Telco is not very helpful at this time. Anyone have any ideas on things I could do? I thought about getting a couple of BRI's instead of POTS Lines.....

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Overall Rating: 5 (1 ratings)
Paolo Bevilacqua Mon, 05/07/2007 - 11:51

BRI is an excellent idea.

You will get more features (DID, caller-id, telco-side call-forwarding, beside getting rid of the crappy unwanted programming.

But while waiting for the BRI, I would try a regular phone on the lines at the punchdown. If no interference, then as you said, shielding the local cabling could improve the situation.

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shane.orr Mon, 05/07/2007 - 11:55

Yeah - I have placed analog butt set to the punchblock taking my system out of the equation and I still get interference as well as I have gone down past my building and jacked in at the pole so it the interference is definitely happening somewhere where I have no control over cabling.

I heard that there might be some sort of one-way filter you can place on the line that might help out but that was a long time ago when I heard that.

Paolo Bevilacqua Mon, 05/07/2007 - 12:09

Having a little bit of experience as amateur radio, I think no simple filter would work. What happens is that cabling (aerial perhaps ?) is picking an harmonic from the transmitter, and once is in there in the wire, you cannot remove it. In theory, a device injecting a waveform opposite to the one picked-up would do this, but it's just theory.

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shane.orr Mon, 05/07/2007 - 12:15

So do you think a BRI would be more resistant to this type of interference?

Paolo Bevilacqua Mon, 05/07/2007 - 12:35

Absolutely, a BRI would not pick any interference.

With pots, the codec is sampling the telephone band, digitalizing whatever signal is in there.

With BRI, the signal is digital already, the codec doesn't do much, just sending the data in IP packets to the phones.

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