Cordless Phone Interference

Dec 05, 2004 5 Replies
J

Certainly. 2.4GHz cordless phones come in various flavors.

  1. 2.4 DSSS: Will coexist just fine with 802.11b/g.
  2. 2.4 FHSS: Will clobber any 802.11b/g on any channel.
  3. 2.4 FM: Will clobber 802.11b/g but only on some channels.
  4. 5.6/2.4 cross band: No clue.

From your question, reading between the lines, it appears that you are looking to buy a cordless phone that will interfere. Normally, a microwave oven is sufficient to obliterate communications, but that burns too much power. While I don't condone such practices, methinks the FHSS (frequency hopping spread spectrum) 2.4Ghz cordless phones will do the maximum damage. Most Panasonic phones are FHSS.

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N

Is there a certain frequency cordless phone that will interfere with wireless networks?


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B

Yes, many cell phones, and home, cordless phones, operate in the 2.4GHz spectrum, as does many wireless video cameras, and links.

Try changing the channel on your WiFi.

Bill Crocker

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N

I want to purchase a cordless phone that will NOT interfere.

Thanks for the help.

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C

I can confirm from personal experience that 2.4 GHz cordless phones do not play nicely with 802.11b/g networks. The problem was reduced, but not eliminated by switching the channel on my WiFi.

Get a 900 MHz phone instead of 2.4 GHz -- it won't cause interference and it will probably sound better too.

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J

The only way you can be sure that there will not be a problem is to buy a 900Mhz cordless phone. Just to add to the confusion, some

2.4Ghz cordless phones confuse DSS with DSSS. DSS means "digital spread spectrum" which could mean FHSS (frequency hopping spead spectrum) or the more desireable DSSS (direct sequence spread spectrum). Anyway, watch out for the acronyms. If you're buying 2.4Ghz, it should be DSSS (Direct Sequence Spread Spectrum).

Also, watch out for cross band cordless phone. Panasonic Giga-Range uses 2.4Ghz and 900MHz. The base transmits on 2.4GHz and receives on

900MHz. The 5.6Ghz version does the same crossband thing with 5.6Ghz and 2.4GHz. I don't recall which band is used to transmit on the base. Anyway, don't assume because it's a 900Mhz or 5.6GHz phone that it does NOT use 2.4GHz.

I once found a table on the web comparing cordless phones which included frequencies, modulation, power, and sensitivity. Of course, I can't find it again. Sigh.

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