I'm experiencing some noise on my phone when it is connected in the wall. There's no noise when connected right in the modem. So I decided to check things out and I noticed something that seems odd to me. My telephone jack uses 2, yes two, Ethernet Cat 5 cables.
(source: max-worlds.net)
As you can see, both blue wires are connected to red wire on the telephone jack and both white/blue wires are connected to the green wire. It seems like an odd setup to me. This is a new house. On a side note, I'm thinking they could have done that to allow an Ethernet network, but we already have a Cat 6 network going on…
So I'm wondering if this is a frequent practice, a recommended approach or a bad job.
Best Answer
Probably you have two or more phone jacks daisy-chained together. One cable goes to wherever the phone line enters the house and the other runs to another phone jack somewhere else in the house.
This is a common practice. I did some pricing online, and it seems that Cat 5e is comparable in price to 4-conductor phone cable, so the builders may simply have used it because they had it to hand.