Splitting a CAT5 cable for telco and data

[marcplante]

I have a single CAT5 line coming into my home office. When I first moved in, I used Wall plug adapters for data networking, and the Cat5 cable has been wired as a telco connection to support our fax machine (which we use maybe 3-5 times/yr).

The Power line networking is not reliable, and I want to reclaim the Cat5 cable to network back to our router (Long house that doesn' support wireless networking particulalry well).

Can I split the pairs in the Cat5 cable to use some of them for data and some for voice? should I give up the Fax function of my multi-purpose machine and look to IP fax for the few instances I need it? (though I tend to scan to PDF and email anyhow).

I think I'm answering my own question, but wanted to understand if I had enough pairs in the CAT5 cable to network. I doubt there will be interference given the relative infrequency of faxing, but I can see my wife demanding to send a fax the day after I disable fax capabilities (She has RADAR that works that way).

Hope this makes sense,

 

[imagoon]

Technically you only need 2 pairs for 10Mb and certain 100Mb connections. However phone signals tend to introduce noise in to the cable that may interfere with or cause framing errors. It is not a 'recommended' method to do it. If it is true Cat5 (not E) the noise resistance of the cable is even lower and may be more problematic.

I personally would pull more cable. I consider pair splitting a 'hack job.'

 

[Modelworks]

Also remember that if that cable connects to a switch/hub you could have problems.

 

[ScottMac]

It's a bad idea; It will generally produce sub-optimal performance, and the ~100VAC ring current (to make your phone ring en you're getting a call) pulses can crosstalk enough to screw up your Ethernet NIC.

 

[iNGEN2]

The Cat5 cable was specifically designed to do just what your suggesting. The problem is that it doesn't worked well with Ethernet speeds over 10Mbs. If you rarely ever use the phone it may be an acceptable compromise, but usually it's just easier to pull a pair of cables. You can use the old cable as a lead line and pull two new ones with Cat5E. Works wonderfully.

 

[bobdole369]

<shudder> Don't do this. Seriously. Find another way.

 

[kevnich2]

You do NOT want to run analog voice and data on the same CAT5 line. Lots of interference, crosstalk, etc. If nothing else, just pull 2 more CAT5 attached to the end of the existing cable and then voila, you have one for voice and one for data. You can use cat5 for voice but do NOT use them for voice and data at the same time. Another option you can look at is a VOIP solution using a DTA connected to a switch, maybe vonage or something like that. I use vonage for faxing - works just fine.

 

[faxon]

best case scenario splitting it will incur some speed degradation whenever the telco is in use. worst case it will fry your NIC and/or completely nullify any data signal being sent along the line. just pull another cable, any network installation professional would probably get fired if they tried to do what you want to do with the modern demands we put on our data networks

 

[Emulex]

use powerline for phone jack - works great

 

[marcplante]

Thanks. I'll pull the extra line. Just hope the builder left the wires free enough to slide...I've had bad experiences with their work in other areas.

Poor power line adapter performance is the reason I started this adventure. Currently, the phone line gets used a couple times a year to send the occasional fax, thoughI suppose a future use or owner may well dictate otherwise.