Is there a simple way to test if a phone jack in the office has power? I just got cable internet and phone service installed, but I cannot get the phone signal into the existing jacks. The one phone works fine direct from the modem, but I need to get the phone signal to the other jacks. Thanks

 

A voltmeter connected between the Red-Green pair works. On hook, should be ~49V.

Here are some inexpensive commercial testers (see bottom of page).

I keep one of these

around for this purpose.

 

Or hook up a led directly to the telco pair. Will seize the line and turn on if polarity is observed.

 

Are the existing jacks and wiring from the Bell system? Most likely they are.

In almost all cases except for AT&T, the installers won't connect their equipment to your old existing phone jacks/wiring, unless you pay extra. So the above checks the other fellows posted will tell you whether or not they are connected.

If your new phone is VOIP based - it can easily be looped back into the existing wiring, although performance will be degraded - VOIP uses a Category 5 (or better) UTP wire pair, while the existing wiring is old-school straight non-UTP.

 

You say you have your cable company providing the telephone service.

If your older traditional telephone wiring and sockets are disconnected from the exchange they will have no power by themselves.
It is now your responsibility to provide that power.

The cable interface box may or may not provide that power for you.

See this extract from Wiki

The second disadvantage it that this service requires power at the subscriber's end. In an emergency, if mains power is lost and without the battery backup unit provided at an additional cost by the cable provider, this telephone service ceases to function. Traditional landline service from phone companies supply phantom power over the communication wires and therefore keep attached devices operational.

http://en.wikipedia.org/wiki/Cable_telephony

We need more details.

 

This thread is all wacky.

A LED directly connected to test - NO. Current limiting resistances are required.

Power -That' means in this case a UPS to operate the VoIP, because it won't be provided by the Telco anymore when your home power is out. Usually, your cable provider will provide the system to do this backup.

If there is no connection from the VoIP box to the house, you wont get phone service in the rest of the house.

Generally VoIp services have a lower REN drive rating, or the ability to drive bells. Telco's is around 5 or 6 model 500 sets. VoIp is about 3. This only affects ringing.
Most modern sets use a LOT less than 1 REN. (Ringer equivalence Number). It should be listed don't the phones.

Polarity to the phones sometimes matters. Modern phones usually don;t care, but it does not mean it's right. Older touch tone pads won't work for dialing out if the polarity is wrong.

Typically, your responsible for the internal wiring.

 

I looped my U-Verse VOIP into my existing unmodified (Bell System era) wiring. I later replaced U-Verse with a Magic Jack. I didn't think it supplied enough current to do so, but I have 4 devices connected with varying REN's . . . to my surprise, it all works perfectly.

I miss the days of POTS and analog cell phones . . . . the old analog systems (even if it was only limited to 3kHz!) was far superior in terms of sound quality . . .