All phone LOCKUP (no dial tone)

I have a 56-K X-2 US Robotics modem that has worked fine for 3-mos. Now when it is connected to the computer all the other phones in the house stay locked-up until they are disconnected and reconnected,even though the modem is not being used. The modem usually works the first time but after the 1st use I get ( Modem bieing used by another dsvice). Has any one had this problem and,or know the solution? Thanks for your help.
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sailwindConnect With a Mentor Commented:
This happened to my old modem before. The problem is that the modem
does not hang up properly anymore. A lot of times, the chip may be fried
to a point where as soon as you turn on the computer, the modem will
go on-hook. You will not be able to force it to go off-hook even with the
ath+++ command. Since it doesn't hang up, non of the other phones
in the house will get a dialtone because your modem is on-hook. You will
not be able to dial a second time because the modem never hanged up
from the first time. This may be caused by an irq conflict, but I've never
found the proof to that. I returned it to the manufacturer and had them
replace it. The new modem worked perfectly. Hope your modem is still
under warranty.
rmayersAuthor Commented:
sailwind,   Thanks for your responce. Your answer makes sense except this modem works ok in another computer and doesn't lockup the other lines.
When did the problem start?

Did it start when you moved the modem from another computer to this one?
Or did it just start doing this one day out of the blue on this current machine?
Did you try putting it into the other computer and see if it works?

If it works on the other computer but not the current one, this may mean that
1: You may have a resource conflict, probably an irq conflict that you don't know about.
    Look at your system resource tab to see if there are any conflict. If you don't see
    any, that doesn't mean there's no conflict. Think about what hardware you have added
    to the computer lately since those may be causing conflict.

2. You may have a bad motherboard which is locking up the com ports. Less likely but
    still a possibility.
The modem has a relay on it which swaps the telephone line with the modem and disconnects the attached telphone.  It is most likely that you received a voltage surge on the phone line which is making this relay stick, and not release so your modme, once connected to the phone line is never released. You can troubleshoot this by using a terminal program and sending AT commands to the modem.  First make sure you can communicate by looking for OK when you issue AT. If that works issue an AT H0 to hangup the phone. If that doesn't work, try other commands to see what does work.  Chances are that the modem will need to be replaced or repaired.
rmayersAuthor Commented:
Thanks *Ireplaced the modem and it doesn't lock up anymore.
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