Can multiple 5.8GHz cordless phone sets co-exist?

January 29, 2006 7:42 AM

Can two separate 5.8GHz cordless phones co-exist in a home?

I've got a Uniden 5.8GHz cordless phone set that I use for business on a VoIP line and I want to get another cordless set (with digital answering machine) for my home land line.

Because I have an 802.11b/g network I don't want it to be 2.4GHz (or 900MHz) so the second phone set would also be 5.8GHz (probably the AT&T 5840).

Will the two 5.8GHz cordless phone sets conflict if they're both in use? My instinct says yes, but I don't know if they've got some sort mechanism to prevent interference. Anyone had experience with this?

posted by iTristan to technology (9 comments total)

I don't have any direct experience with 5.8GHz phones but my understanding of the mechanics of cordless phone technology suggests that each phone has multiple channels (mild variations of the 5.8GHz range, ie. 5.800001, 5.800002, etc.) so that even if they conflicted, you could change one phone to use a different channel than the other phone.

I have three different 900MHz cordless phones which don't affect each other at all.
posted by ajpresto at 7:51 AM on January 29, 2006

Uniden's phones are frequency-hopping spread-spectrum, and two different systems should automatically stay out of each other's way. A FHSS phone 2.4 GHz phone will also stay out of the way of a WiFi network -- I use a Panasonic 2.4 GHz phone and it works fine with my WiFi. But I'm looking to upgrade to a 5.8 GHz system eventually anyway, because that's where all the cool new features are coming out.
posted by kindall at 8:50 AM on January 29, 2006

two different systems should automatically stay out of each other's way

Being pedantic, no they don't. They stay out of each other's way by pure chance by constantly changing frequencies at random. They do occasionally collide, but only for a fraction of a second until they next hop to new frequencies.
posted by cillit bang at 9:08 AM on January 29, 2006

(More helpfully, they do this exactly so you can use more than one piece of equipment on the same band without problems. Go for it Tristan)
posted by cillit bang at 9:11 AM on January 29, 2006

They stay out of each other's way by pure chance by constantly changing frequencies at random

This was part of my concern/question. So really, the frequency hopping is not so much an intelligent "I see there's interference here, so I'll move to another freer frequency"-kind of behaviour, as it is a random "just keep it moving and nothing will bother us" sort of thing.

Not nearly so intelligent, but enough to generally keep the wolves at bay?

In the end, the two sets should rarely really collide in any meaningful way then?
posted by iTristan at 9:12 AM on January 29, 2006

Sadly the Wikipedia article on this is complete crap. The general idea is that each device operating in a channel appears to the other devices as random background electrical noise, which they're designed to cope with. As I said in my second post (which you may have missed), this is a great way for two to more devices to share one band.
posted by cillit bang at 9:26 AM on January 29, 2006

Excellent, that's what I was looking for. I thought this might be the case (the alternative was that they might just bash into one another) but wanted to pass it my the meta crowd first.

Thanks so much for the tips all. I'm going to go for it.
posted by iTristan at 9:37 AM on January 29, 2006

cillit bang, if you know that the wikipedia article is crap, complaining about it doesn't help. Please fix it!
posted by Caviar at 10:27 AM on January 29, 2006

I've sworn off editing Wikipedia because watching stuff you've worked on being slowly destroyed by idiots is bad for the skin.

(Though my articles on DMDs and DVI* are largely intact)

(* actually I just removed a load of nonsense from this one)
posted by cillit bang at 11:59 AM on January 29, 2006