I’m trying to find out if the phone line is working at a remote house. (We’ve had extreme power outages here for over a week, and I’m sure that the power is still out at this house) I call and it rings continuously. That seems to indicate that it is working.
Am I correct in assuming that a dead phone line will return a busy signal when called?
A dead line should get you that rising 3-beep error tone and an automated message stating that the number you have dialed has been disconnected, then it may instruct you to check the number and try again. It may ring a few times before this happens.
Is the phone you’re trying to call wired or is it a cordless?
I ask because wired phones are powered by electricity coming from the telco - you can use one of those old phones when the rest of the power is out (provided the telco is still providing power).
Yes. Landline and wired. I’m just wondering if when I get back to the hotbox tonight if I will have about 4 hours of dial up internet until my laptop dies. 
There’s dead, and then there’s dead. If by dead you mean no service at all, you’ll get the disconnected number recording. If there is service, but the lines in the house aren’t connected properly to the network interface device, the caller will hear either the ring tones, or get a busy signal if something is shorted.
If you’re hearing ringing sounds, the line going to the house probably works. The inside wiring probably works, too, but at worst you should be able to connect to the test jack in the network interface device to get out.
This page shows a pretty clear explanation and diagram of how to get to the test jack:
No. There is service in that I paid the bill. 
And it normally works. Power has been out in that area for 7 days now, so if the telco has no power, then the phone won’t work. I’m just wondering since it rings (and I let it ring 10 times) that means the phone is for certain working.
Didn’t it used to ring busy if there was no power supplied to the line? I wouldn’t think that I would get the 3 tone–disconnected, no longer in service message unless it was really and truly, disconnected and no longer in service.
Assuming there are at least two different phone company offices involved, the ringing you hear is being generated at the office closest to you. It’s not coming from the far end telephone.
The phone company supplies 48vdc to the far end phone set. If the line tests “good”, your local office will send you a “ringing tone”. You may be sent a “busy” signal of 60 ipm (interuptions per minute) if the phone is in use. You may be sent a “fast busy” of 120 ipm if the phone company doesn’t have a transmission path available to connect to the far end phone line.
I assume that since you do get a “ringing tone” when you call the number that there is a working phone at the far end. The house may have been looted of everything else of value or flooded just below the point where the phone base would be under water, but the phone still works.
That’s entirely possible. So, to hear a ringing tone, there must be a phone connected? What would I hear if the phone lines were working, but no telephonic device was connected at the house?
Side note: I may actually have power. The neighbor does and he is going to check on mine…
If there is no phone present or a broken wire then the phone will still “ring” from the caller’s point of view.
A ring signal alone is not confirmation that the line itself is good all the way out to the house.
Is there an answering machine connected at your home to the phone? I’ve found that is the best way to verify the line is working and the power is on.
phone companies are able to generate their own power independent of the grid.
As it happens, we had a blackout yesterday. Our home phones are cordless, and when I tried to call home, I got a busy signal.
A dead phone, or: one with no dial tone could be caused by a short. a short can be something as simple as the two wires (tip and ring) that make up a phone circuit touching due to broken installation or mold growing inside a jack and causing the pins to short. In a short condition a caller would receive a busy signal when trying to call. The above posters are correct, when calling someone, the ring you hear is generated by the Central Office and not the other telephone.
Normal phone: Brrrrrinnnnngggggg … brrrrrinnnnngggggg … brrrrrinnnnngggggg …
Dead phone: *Doo DOO DEEEEEEE … the number you have call has been disconnected or is no longer in service … *
Undead phone: *Brrraiiinnnnzzzzz … brrraiiinnnnzzzzz … Brrraiiinnnnzzzzz … *
No, but you did have a phone connected. You can request that the local far end phone company test the line to be sure. The testing is more than likely automated.
When your phone is “offhook”, a switch connects the circut to the phone company and dial tone is then connected to your line.
When receiving a call, the phone company supplies voltage to operate your phones “ringer”. That means that they can also test to see if there is a complete circuit from the phone company to your phone and back to the phone company. Each phone/fax has a ringer equivalence number (resistence). Add too many phones (5 or 6 ?) and your phones won’t recieve enough voltage to actually ring but your caller will still hear ringing on their end.
The telephone company supplies it’s own electrical power seperate from the electric companies power. Phones can work when the lights don’t and vice versa.