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Community Member

AP interference


I would like to ask if i installed a 900Mhz cordless phone would it still interfere with my Cisco AP 1231G? though, i did not test our cordless phone, but i turned it off as i operates in 2.4GHz frequency



Hall of Fame Super Red

Re: AP interference

Hi Eduard,

The 900Mhz cordless phone should have absolutely no impact on the 1231AP. We use many Plantronics CS50 cordless headsets (@900Mhz) in our Wireless environment (which includes 1231AP's) with no problem at all.

We did try connecting a 2.4Ghz cordless phone once in our lab and everytime the phone rang it would disconnect the wireless session we had open :)

Hope this helps!


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Community Member

Re: AP interference

This thread caught my eye. We are in a building that has other tenants. What can we do to minimize the effects of their 2.4ghz phones?

Community Member

Re: AP interference


If are facing interfacing problem mean if you have many access points -b access point and there are two client one is b and second is a g then g will create problem with b, it will drop b clients rate dramitacly....


SR.Wireless Engineer


Re: AP interference

This can be a real trick.

Your first defense begins before the wireless ever gets installed; a good, comprehensive site survey. It should be able to identify likely interference sources. You can't make a work-around for something you don't know about.

Next is the selection of antennas. Clever use of directional antennas (sectors, patches, and panels) can negate the interfering signals or (worse case here) overpower the interfering signal in your area of use.

You have to strike a balance with the above to also cover security and "leakage" of your signal to places that a bad guy can capture your signal. Of course, it is also bad to interfere with your neighbors, if you can avoid it. They might decide you are a rogue AP and initiate some wireless security that will cause your system to continually disconnect / drop your clients.

That's really about it: know where the interference/interception points are, engineer your RF pattern accordingly with the right antennas and power settings, and try to keep the signal as local as possible.

Good Luck


Community Member

Re: AP interference

Thank you for your reply. That is the basic approach we have taken. We found that there was so much b/g in our building that 802.11a was the right choice. It was more costly, since we had to upgrade the cards, place more access points, etc. We now just us the b/g for guest access and the a for our internal access.

One last question though, what tools are good for measuring non 802.11 interference, such as phones, microwaves, etc. I know there are devices such as the yellow hornet (I think that is the name) but they are very expensive.


Re: AP interference

Generally, I use

1) a cheap AM radio tuned to a null stationto check for field noise (noisey motors, electrical fields, bad ballasts, etc) AM radio is good for hearing common noise.

2) NetStumbler is good for general radio traffic and some non-802.11 interference

and / or

2b) Kismet (linux based) it can detect the other traffic and, with the Master/Slave setup, can be used for WIDS as well) a little more capable than NetStumbler, but a bit harder to setup

3) TamoSoft CommView as a wireless packet analyzer / "sniffer". CommView is much less expensive than the other analyzers (~US$600.00 versus thousands for the others)

CommView will show corrupted frames and give you traffic stats (corrupted are Red Text, Valid are Blue, for example) with that and NetStumbler (and / or Kismet) you can usually paint a pretty decent picture of the ambient RF noise.

I'm sure there's other / better / more sophisticated stuff out there, but so far, this is all I have needed.



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