That is an odd problem. I wonder if your line levels are bad, but the first thing I thought of was your phone itself might be faulty or there might be some sort of odd call waiting thing going on?

Hi pjb999,

I don't have call waiting. I have an answering machine on a portable phone, plus several portable phones and several land lines. At first I thought it was one of the land lines, because there was one time when the others worked, but this one was dead. But as soon as I called from my cell phone, the bad phone worked again.
But most of the time, its all the phones.
What's a line level?

It could be a bad or loose connection somewhere in or between the interface box and your phone.

When you recieve a call, the "ringing" voltage is higher than the "outgoing voice call" voltage,
maybe just enough to "re-connect" the bad connection.

Hi regus, That's what I was deducing too......although I didn't really understand the "how" of it. It just felt that calling the phone with my cell phone somehow cleared the line.
I just don't want to spend a fortune having AT&T telling me it was something simple. I don't have the line-backer insurance thing, so they like to stick it to the people who don't! lol.

How many pieces of equipment, or telephones, do you have on each line? There used to be a limit as to how many you could put on a telephone line before problems would start showing up. With you being on a rural line, this could be a problem.
it sounds like it's going to be a process of elimination, one telephone at a time, until you find out which one is causing the problem.

Here is a link that might be useful: Telephone Trouble and Troubleshooting

Hi Jim,
Thanks for that link. It looks very helpful.
On our second line is only the computer, and it never seems to have problems.
On the first line, we have 5 phones.....oops, I forgot the line out in the barn.....so 6 phones. I'll try disconnecting the ones we hardly ever use and go from there.
Our interface box looks a mess on the inside. It wouldn't surprise me if the problem is there. But I'll try to figure things out inside the house first.
We live about 1/4 mile off the road, so there's all that cable in the ground, so there's probably alot of places that things could go wrong. Plus, the big junction box down the road is always having problems with mice, wasps, rain,etc.
Thanks for your help.

Your problem is most likely in the interface box. Although it would be the phone providers responsibility, you can fix it easily if you care to. You have every indication of a common bad (high resistance) connection. You'll have to access the phone companies side of the box. If you look to where the wires are connected, you'll probably see green fluff on one or bothe connections. Chances are, the copper wire has been eaten through and has or is coming loose. Carefully remove each wire, one at a time so you don't lose track of where they are connected. Also be careful of the terminal stud if it is badly corroded. If it is in bad shape, loosen it just enough to unwrap the wire and remove it. Clean the terminal, strip back some insulation and reconnect the wire. You'll find a very clean noise free connection...unless the same problem exists at the "big box down the road".

Thanks irisman,
I will check that out and probably be back with more questions! I think if I find the phone company's stuff in bad condition, I might just call them, as we're not very good fix-it people here, and I wouldn't want to end up messing things up worse.
Thanks for your help, and I'll let you know what I find.
Even the customer's side of the interface box is a mess. Plus, when I insert my own phone line to check it out, its hard to get it in there straight, so it wouldn't surprise me if the interface box is the problem.
Thanks!