Modems lose dial tone on AIX, require power cycle to restore

I've got an application running on AIX v4.3.3.0 that uses some external US Robotics 56k modems for dial out.  It was relatively problem free for about 4 years, and in the past couple weeiks, the external modems have started losing dial tone.  I've had the phone lines checked, and they are working.  There are four external modems, and they all eventually die (one at a time, sometimes within hours of each other, sometimes days apart).  The only way to recover the modems is to turn them off and back on.  Resetting them programatically doesn't work, rebooting the server doesn't fix anything.

It seems unusual that all four modems would have problems at the same time, but I can't think of what would be causing this from the server end.

Any idea?  Any diagnostics that can be run from the server?
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Connect a phone to the phone port on the back of the modem, pick it up and see if you hear dial tone.

It could be that the modems are starting to show their age and something inside is going bad.

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
jjmartinAuthor Commented:
It could be the modems... and I'm gettting some new ones, but it just seems odd that all of them would start having problems at virutally the same time.
Are both the power cords and modem cords going through surge protectors?  How old are they?

Surge protectors wear out.  How long they last is dependent on how many power surges/lighting strikes they have had to suppress.

If they old, or you don't have any, have you had any recent power issues or lighting storms in your area?

Powerful Yet Easy-to-Use Network Monitoring

Identify excessive bandwidth utilization or unexpected application traffic with SolarWinds Bandwidth Analyzer Pack.

jjmartinAuthor Commented:
The hardware is in an extremely secure environment.  The likelyhood of any type of power event causing a problem is very very low.  There is another server in the same rack with that is setup virtually identical to the one with problems, and is under pretty much the same load, if not greater.  It's not having any problems, and it went into service at the same time.  it's just the modems connected to this one server.
Modem hang is modem internal problem. Easiest to solve with firmware update.
If crashes persist after update - you have to trace down what commands caused them.
jjmartinAuthor Commented:
This is what finally happened.

There are three modems connected to the server.

1 directly connected to an on-board serial port. (modem 1)
2 connected to an 8 port serial port expansion card installed on the server. (modem 2 and 3).

If I enabled modem 1, it would die after a few hours (no dialtone).  Then modem 2 and 3 would follow several hours later (but not at the same time).

If I left modem 1 disabled, then modem 2 and 3 would work just fine.

Cycling the app that uses the modems, and rebooting the server wouldn't recover the modems.  The modems would have to be physically powered off and on.

I've replaced all the modems, and now all 3 are working fine, still connected to the same serial ports.

I agree, that is weird.
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Networking Hardware-Other

From novice to tech pro — start learning today.