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Can a single UTP cable used for both telephony and network at the same time? As far as I know a UTP cable has 8 wires, the network jack requires 4 wires and the telephone jack 2 wires.

Is this possible? Maybe there's going to be a lot of interference?

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up vote 2 down vote accepted

Technically, yes but it will be a non-standard use of the cable.

You can get adaptors to do this - for example:

Can't comment on noise/crosstalk issues as I have never done this and wouldn't consider it at all in a corporate environment.

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this looks perfect for me! thanx – Panagiotis Jan 30 '11 at 10:23
Note that if you do this you won't be able to do gigabit ethernet, as that requires all four pairs. – Moose Jan 30 '11 at 17:06

This will not be legal in most countries.

The telephone signalling is classified as TNV (-1, -2 or -3) according to international standard IEC 60950. And your network is classified as SELV.

The two systems must be separated by double insulation or reinforced insulation.

Running the two systems inside a single cable sheath would mean there is only single insulation between each system (a single layer).

Don't do this. The effect on electrical safety of the telephone system as well as your network COULD be compromised, and if a fault were to find its way from one system to another and people got hurt the consequences to you would be very unpleasant.

You should have telephone and data cabling done by a licensed operator who knows the installation rules.

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This raises a good point, but the regulations do vary from country-to-country - for example, from the Australian regs (AS/ACIF S009:2006): "Note: 9.3.2 ELV, SELV, TNV and limited current circuits may be carried in the same cable (i.e. share the same cable sheath).". There's no harm in checking local regs though. – Linker3000 Jan 30 '11 at 11:36

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