DSL interfering with 5.8ghz phone even with line filter

May 12, 2007 8:12 AM

We recently purchased a Uniden exai-5580 5.8ghz cordless phone. The incoming volume is terrible: low and staticy. The interference seems to be coming from our DSL line. How do I fix it?

I recently discovered that if our DSL gateway (a 2Wire HW1000) is unplugged the problem goes away. While this gateway puts out an 802.11b signal I believe the problem is actually the wired DSL signal, as I tried disabling the wifi and nothing got better. We do have a line filter installed, the generic one that came with the gateway. Our previous 2.4ghz phone (which was also a Uniden model) never had a problem. Any ideas on how we can get rid of this interference, short of toss the phone or disconnect the DSL every time we want to talk on the phone?

posted by Lentrohamsanin to Technology (9 answers total)

did you install the DSL filters on your phone lines? Any phone jack with a device plugged into it needs to have a DSL filter installed on it. The box from the phone company should have had several in it.
posted by cosmicbandito at 8:49 AM on May 12, 2007

If the old phone could handle the modem's EM interference with no problems, Id assume the shielding on this new phone is sub-par and return it for a new one or a different brand.
posted by damn dirty ape at 9:02 AM on May 12, 2007

Also, the line filter is to protect the dsl connection, not the voice connection so it shouldnt matter in this case.
posted by damn dirty ape at 9:03 AM on May 12, 2007

You should be able to request the phone company do a "line noise" check on your lines (done at the pole, atop big ladder) without a charge, citing data/voice interference..
posted by vanoakenfold at 11:01 AM on May 12, 2007

Some modems will interfere with the phone line more than others. I don't think this is a case of EM interference at all, just leakage of the DSL signal into the audible band of the phone line. Different phones have different frequency responses, so changing phones can make the DSL signal more/less obvious.

I've been experimenting with a couple of DSL modems lately, a 2wire and a speedstream. The 2wire interferes with my old traditional dial phone, but the speedstream does not interfere. On the other hand, neither modem interferes with my 2.4GHz cordless at all.

Try putting two DSL filters in series on the effected phone. It reduced the noise to a tolerable level for me.
posted by Chuckles at 12:12 PM on May 12, 2007

Are your cordless base station and the DSL modem sitting on the table right next to each other? Try moving them apart from each other. Sometimes just a foot or two will make a difference on interference.
posted by JackFlash at 1:11 PM on May 12, 2007

Response by poster: did you install the DSL filters on your phone lines?

Yup.

Are your cordless base station and the DSL modem sitting on the table right next to each other?

Nope. They're in different rooms.

I've been experimenting with a couple of DSL modems lately, a 2wire and a speedstream. The 2wire interferes with my old traditional dial phone, but the speedstream does not interfere.

Funnily enough I just bought a speedstream off of eBay, so I can use a proper router and also upgrade to 802.11g (the 2Wire gateway is apparently an unsupported bitch to put into bridge mode). Maybe that will make a difference. I'll try the two filter suggestion too.
posted by Lentrohamsanin at 3:28 PM on May 12, 2007

Also, the line filter is to protect the dsl connection, not the voice connection so it shouldnt matter in this case.

Er, the line filter is to stop the high-frequency DSL signal getting into the phone & (de | cross) modulating down into the audible range, as well as preventing that effect from reducing the DSL signal level to the modem (which, at best, causes both the modem & dslam to wind up their power levels to compensate, adding more noise...).

To be very clear and sure about this: your modem doesn't need a filter on it. Every other phone device on the same line/number (not just the same socket) does.

Having said that, this sounds more like wireless interference - 5.8GHz being the second harmonic of 2.4GHz.
posted by Pinback at 3:45 PM on May 12, 2007

5.8GHz being the second harmonic of 2.4GHz

That would actually be 4.8 GHz.
posted by kindall at 8:53 AM on May 13, 2007