Cat6/Telephone

[Invader75]

Hi,

We've just had an annexe built. I supplied the Cat6 cable for the electrician to connect up. Just been down there and it appears he's connected it up as a phone line. 🤔

Couple of questions. Obviously I can change the connector and socket over easy enough. But, as we don't yet have a phone line down there yet, is there anyway to use the Cat 6 to carry both a phone signal and internet. I know this sounds like a stupid question, and it probably is. ;-)

[Ian.M]

Although slower ethernet modes only need two pairs, its a *really* bad idea to mix ethernet and telephone in the same cable as it drastically increases the risk that you'll fry everything on your network if there is a lightning strike near your house or the phone line to it. 

[Invader75]

Ok. Fair point. I must add we're in the suburbs of Cardiff, Wales, with the annexe being single story timber frame.

[FrankE]

Don't mix them in the same cable. There's 48V on a telephone cable. The ring signal is 50V ac. There is a risk of crosstalk.

[Invader75]

Ok, guess I'll have to run a phone cable down to the annexe separately.

Thanks for you help

[madires]

Or go for VoIP. BTW, most installations use dual RJ45 wall sockets, i.e. two ethernet cables.

[Monkeh]

Or go for VoIP. BTW, most installations use dual RJ45 wall sockets, i.e. two ethernet cables.

Often simply because it's insane to run a single cable. Run two, if both are good, free socket!

[Brumby]

If you're going to run a second cable, I'd run another Cat6 - and wire up both for ethernet use.  This allows you to use either cable for digital (ethernet) traffic or analogue (phone) signals.

You can then use one as a phone line by simply having the appropriate patch cable.  You can buy phone cables with RJ45 on one end and RJ12 on the other.

Then, if you want to move to VOIP, you can change the usage of the second line without any rewiring or changing your existing ethernet setup on the other line.  Also, with two ethernet lines, you have redundancy and/or expansion - which is never a bad thing.

[edavid]

Don't mix them in the same cable. There's 48V on a telephone cable. The ring signal is 50V ac. There is a risk of crosstalk.

Not really, it's twisted pair.   You can mix 100BT and voice on the same CAT5 or CAT6 cable and it works fine.  The lightning issue is worth some thought though.  Of course if the phone line is coming from an ISP provided VOIP modem, that's not an issue either.

[Ian.M]

Ethernet signals can degrade ADSL on a pair in the same cable.  However ADSL can be degraded by just about any source of RF noise, so, leaving the lightning damage issue aside,  the best advice is to split it off with a filter at the demarc point so there s no ADSL signal on any of your home phone wiring and run dedicated STP cabling to the modem for it.

[MavMitchell]

Splitting is routinely done, although its not ideal as described above.
It is limited to 100Mbps and will interfere with DSL signals as indicated.

https://www.lanshack.com/QuickTreX-VoiceData-Splitter-Pair-P1564.aspx

[edavid]

Not sure why people are bringing up DSL... it seems like a red herring since OP did not mention it.

[Monkeh]

Not sure why people are bringing up DSL... it seems like a red herring since OP did not mention it.

Because DSL is by far the most common way of getting online in the UK.

[dave_k]

We've just had an annexe built. I supplied the Cat6 cable for the electrician to connect up. Just been down there and it appears he's connected it up as a phone line. 🤔

Judging by the use of the blue and orange wire I wouldn't be using that electrician again if he cannot even identify what a "pair" is! 

[Whales]

You can buy phone cables with RJ45 on one end and RJ12 on the other.

N.B. not necessary.  RJ12 cables will fit and click into RJ45 sockets just fine (as will a few other RJ variants).  They are also pin-compatible in that the middle 4 wires of ethernet RJ45's are arranged to match common phone connector use.   It's a clever design that in practice maintains compatibility.

If you plan to use RJ45 sockets for anything other than ethernet: label them to hell and keep them away from normal ethernet ones.  You don't want anyone blowing network cards (or worse) by plugging into a phone line.

+1 to the advice of not running phone lines in the same cable jacket as anything else that doesn't have lightning protection.  Ideally not even in the same bundle of cables.  If you are desperate then there might be some dedicated lighting arrestor devices you can permanently install, no idea how effective they are.

[Ian.M]

Not sure why people are bringing up DSL... it seems like a red herring since OP did not mention it.

Because DSL is by far the most common way of getting online in the UK.

... and the ISPs usually supply a bundled 'kit' to domestic customers for self-installation with a combo DSL modem/router typically with four LAN ports,and a few DSL microfilters to go between phone equipment and the existing phone sockets to keep the DSL signal out of equipment that coud adsorb it or otherwise mess it up.  You plug the modem/router into the DSL port of one of the filters.

Done as instructed (just described), that leaves all phone wiring in the property carrying the DSL signal and picking up interference.   Typically, if the house was previously wired with a lot of extension sockets, fitting a whole house DSL filter at the demarc (master socket in the UK)  gets you a significant speed increase!

[madires]

N.B. not necessary.  RJ12 cables will fit and click into RJ45 sockets just fine (as will a few other RJ variants).  They are also pin-compatible in that the middle 4 wires of ethernet

They do, but the smaller plugs will bend the outer contacts of the RJ45 socket causing contact issues later on when inserting an RJ45 plug. Get a cheap RJ45 crimp tool and a few plugs.

[johnkenyon]

If you're going to run a second cable, I'd run another Cat6 - and wire up both for ethernet use.  This allows you to use either cable for digital (ethernet) traffic or analogue (phone) signals.

You can then use one as a phone line by simply having the appropriate patch cable.  You can buy phone cables with RJ45 on one end and RJ12 on the other.

Then, if you want to move to VOIP, you can change the usage of the second line without any rewiring or changing your existing ethernet setup on the other line.  Also, with two ethernet lines, you have redundancy and/or expansion - which is never a bad thing.

Hint 1 - RJ45 to BT431 adaptors depend on the phone line being on pair 1 (i.e. the two centre pins)
Hint 2 - you can usually insert an RJ11 lead directly into an RJ45 socket - again make sure the phone line is on pair 1, and you can sometimes get away without having to install an adaptor
(my UK example: I have an ADSL filter where the phone line enters the house, a short RJ11 to RJ11 lead which plugs into a Cat6 ethernet extension back to the "server room". In the server room another RJ11-RJ11 cable is used between the patch panel and the DSL modem. This also has the advantage of dropping the unbalanced "ringer" wire along the extension cable, which gives a minor boost to the DSL line rate)

[Invader75]

Ok, slow down guys! 

This is in the beginners section.

The install is done, cat6 was run underground with the rest of the utilities so I can't add another cat6 unless I just run it down there externally. Likewise with a phone line.

The electrician wasn't chosen by us, he came with the people who were installing the annexe.

I just want a simple solution, or answer, to the problem.

Many thanks.

Mr Layman ;-)

[madires]

Do you need the phone line for a telephone or something else, like DSL for example?

[Invader75]

I need a phone line for a phone and ethernet for a router. 👍🏻

[madires]

Would a cordless phone work for you?

[Invader75]

Cordless fine but probably too far away from the house for the signal to reach. Approximately 15 metres.

[madires]

15m shouldn't be a problem for DECT. Another solution would be VoIP. The telcos are migrating their telephone networks to VoIP anyway.

[soldar]

The install is done, cat6 was run underground with the rest of the utilities so I can't add another cat6 unless I just run it down there externally. Likewise with a phone line.

No conduit? Is that even legal?

There is weatherproof phone cable, of course. You can just run a new line.

The electrician wasn't chosen by us, he came with the people who were installing the annexe.

I just want a simple solution, or answer, to the problem.

The electrician was not chosen by you but what you wanted done was presumably specified by you. The time to ask for simple solutions was when you specified the work to be done.  Now the simplest solution is probably to just run another cable.