Using AT&T EP5962 2 line phone for business with 3 base phones and since changed the local cable company for phone services we are unable to see on all phones when someone is on the line at another ph

That means that there is a problem with the wiring from the base of the phone to what ever service you are using. If you are using cable television, then the modem connects to the house wiring. IF you are using telephone company service then it connects to a box called a demark.

I assumed when you say all phones are operating means there's power and are charging.
1. There could be some phones that are loading the Tel line. Disconnect all phones and plug it one by one while checking the dial tone. If all phones gives busy tone, there coulb be a problem in the Trunk line or the Tel Company line.
2. There could be a short or resistance in the line. Check the connection in junction box between your house and the Tel Company cable.
3. If you have an analog Tel set, you can check the dial tone directly from Tel Company cable that comes in to your house.

I hope this helps.
Best Regards.

1. Check your connection. Make sure your phone is connected to the phone line.
2. Change phones. Plug a corded phone into the phone line where you are experiencing problems. If the problem is resolved, the problem might be your phone, not the line; if it's a portable phone, it could have a signal problem. Make sure to change phone cords along with the phone to rule out problems with a phone cord.
3.Disconnect all extra phone equipment that plugs into your phone line, including modems, fax machines and additional phones. Leave only one corded phone plugged into your phone line. If the problem still occurs, plug your phone into every phone jack in your home to verify the problem is throughout your home and not isolated to one outlet. If your problem was resolved by unplugging devices, attach each device, one by one, to see if the problem returns. If it returns when you plug in one device, you know your problem is with the device.

4.Call from an outside line. You can call from a cell phone or another land-based phone line. If the problem still exists, the problem may reside in the phone lines outside your home.

5.If steps 1 through 4 do not fix your phone line problem, call the phone company from an alternative phone line. Discuss the problem you are having with your phone line and all the steps you have taken to check the phone line for problems. Your phone company will probably call your phone line to run some diagnostic tests. Based on these tests, they can determine if the problem is inside or outside your home. If the problem is inside your home, you might need a professional to diagnose the problem using line-testing equipment. If the problem is in the line outside your home, the phone company is usually responsible for fixing the problem.

(I am assuming you are a business.) You don't have a power problem, you have a line trouble to or inside the phone itself. Phones operate with two wires: tip or green wire transmit the outgoing sound (voice); the ring or red wire transmit the incoming ringing signal. Your ring side is shorting out after the first ring. This short can exist in a local central office that transmits your dial tone to you; can exist in the underground/airial wires to your buiding; can exist in a wire closet (a riser wire closet from the basement wire closet to your floor); or in your the very base of your phone. You can have your service provider to verify the ring side of your service at the basement equiptment room. They may charge to verify any further; however, it is common to have this short appear from the central office. If the central office is transmitting a good ring side signal, pay a local communications company to verify your line from the basement entry point to your office(s). NOTE: FIRST TEST OUT A CORDED PHONE AND SEE IF IT RINGS OK...THAT WILL ISOLATE THE TROULE TO YOUR PHONE IF THE CORDED PHONE RINGS OK. GOOD LUCK.

This is posted under a "cellular phones" heading, but I'm going to assume you have cordless phones that you're trying to hook up again.

Remember that the base unit needs to be plugged in to power and also to your telephone line. So be sure the base location is near an AC outlet and that there is a phone jack somewhere nearby. You may also want to verify that the phone jack you'll be using is actually working. It may not be connected, or may be wired to a second phone line. You never know when you move in. Plugging in a plain old corded phone will let you check for dialtone.

Plug in the base unit power, connect it to the phone jack and put the handset on the base and you should be back in business. If you have a phone system with multiple handsets, you'll need to place each one on the base to register it.

This should get your phones working if you have a regular landline coming in to your new home. If you use an Internet phone service like Vonage or you have service from a cable company, you may have to get someone to check the wiring if you don't have dialtome appearing at the jacks.

Good luck and thanks for using Fixya!

There are no lines available. Have someone test dialtone on all your lines.

If you have a phone that works off a broadband modem, that is a VoIP phone. That will not work with a home phone line. I'm assuming Verizon is your local Telephone carrier that provides your local dial tone.
The broadband modem would have the phone number of whatever VoIP phone service you have.

Fax machines must have a standard analog phone line. They won't work on a digital line and can actually be damaged if hooked up to one.

sounds simple
3 things to look at

lets start with obvious i hope you have manual for phone still cause typen instructions for deregistering phone is long type
the reason phone could be showing its still in use is because phone needs to be deregistered and then reregistered back on the hand set base

the other thing is one of your neighbors has tapped your phone line giving you this busy signal

or say you still using dial up on your comp this will show a busy signal cause its using your phone line to get online

unplug everthing from all jacks in the house. call your # a couple of times. if the line rings, plug everything in 1 at a time, but call again after each hook up. if the line goes dead or is busy, that phone you just plugged in is the problem. [ a short in the phone, computer, answer machine, or any piece of equipment plugged into the phone line.] if the line is busy when everything is unplugged, call your phone company. there maybe a problem with your inside wire.there also maybe a box [called a nid] inside your basment/garage or on the side of your house, where you can plug your phone directly in, bypassing all the jacks in your house
hope this helps.
wg