Help!! Is my modem possessed?

Question

I have a 1-yr old iMac G5 with an internal modem. I use a dial-up internet connection in a rural area with ancient phone lines. After a storm last week, my modem (I think) seems to have taken on a life of its own and interferes with our phone service (we have only 1 line). Most of the time, if the phone line is connected, we have no dial tone, even if the computer is off. Once I unplug it, dial tone returns. I can usually connect to my ISP, but if I disconnect, I will have no dial tone until I unplug the line. If I disconnect, then try to reconnect, I will get a error message that no dial tone is detected.
Phone company said there was a short in the jack where the computer is plugged in, but I think that was because the computer was actually plugged in at the time. A phone plugged in to that jack will work fine. I had the same problems when I plugged the computer into the test jack outside the house. I feel like we have tried everything and the problem keeps pointing to the modem, but I don't know/understand why. I would really appreciate any help that anyone can give.
iMac G5   Mac OS X (10.4.3)  

Answer 1

Hello,
I would suspect that the modem itself is partially damaged. I've seen this with bad modems before. It's possible for a damaged modem to hold the lines (due to a short) even when the computer is off.
Often people will neglect to protect the phone lines leading to their computer, and that is a major potential problem.
As you likely know, you should be using your computer with a high-quality surge protector to prevent power surges from damaging the computer.
But, most people completely overlook the other connections. The simple fact, is that anything connected to your computer can pass a power surge to the computer.
So, if your printer is not on your surge protector, and it is connected to your computer, then a power surge could hit the printer and then travel through the cord to the computer. That surge could then pass through the circuitry in the computer and damage whatever it happens to hit.
The same is true of your telephone line. Your telephone line should also be run through a surge protector before going to your computer. Failure to do that means that you might as well not even provide power protection to your computer.
Basically, anything you have connected to your computer should be connected to a high-quality surge protector. Even phone lines, ethernet lines, and whatever else.
Many high-quality surge-protectors include a jack to connect your phone line through that will provide protection.
I use both a modem and Ethernet / DSL. So, I have both my phone line and my Ethernet cables going through a surge protector before reaching my computer.
I actually have it doubled-up. My phone line is run through a surge protector right at the point it enters the house. Then, from the surge protector, it goes to my phone jacks. So, every phone jack is protected.
Likewise, my DSL line is connected after the surge protector, so it's protected as well.
Then, before each computer, I have a surge protector on the phone and Ethernet jack leading to the computer.
It may sound like a lot of trouble. But, if you leave one point of entry into your computer unprotected, then you could have the entire machine damaged by a surge that enters through that weak spot.
So, protecting it important.
In your case, you sound fortunate to have only had the modem damaged. A surge could have passed through the modem and gotten the rest of the computer.
So, first thing I would do is get your computer and everything else that touches it on a good high-quality surge protector. And, also the phone line.
Since the modem is damaged already, there isn't much you can do about it (it's built-in / non-replaceable).
But, you can restore functionality by purchasing Apple's USB modem. It's about $49.
You could plug that into your USB port and then use it to connect to the Internet. Unfortunately, USB modems sometimes have a less reliable connection to the Internet. But, I think that's your only option at this point.
If you took your computer to the service center to repair the modem, they would just want to replace the entire logic-board. And, that's about $700 (or more). And, it's not warranty related since the damage would have been caused by an electrical storm.
I hope this helps.
Let us know if you have other questions.
P.S., if you'd like, go ahead and click the "Helpful" or "Solved" buttons on any of the posts / replies above if you feel they were helpful or adequately answered your question.