Same Problem With Three Different Modems

I just built a new system based on a Gigabyte GA-7VM400M running XP Pro and I'm having similar problems with three completely different modems:

Pragmatic I56PSP-F30 (PCTel PCT789T-C1 Chip)
Pragmatic I56LVP-F00 (Agere 1646T00 Chip) Lucent Winmodem
Dynalink 1456VQH-R Int1 (Rockwell R6785-62 Chip)

Basically XP recognizes and installs them with no problem.  I query them and they respond.  I can even dial-up to my ISP and they seem to work great.  I can surf and download without any problem.  

But then the connection either stalls or disconnects after between a couple of minutes to 15 or 20 minutes.  After that I can't get the modem to reconnect.  It dials, I hear the handshake, then 30 seconds of silence, then verifying user name and password for 30 seconds plus, then "Cannot connect the phonebook entry.  Error 756:  The connection is already being dialed." then "Unable to establish a network connection."  

Another modem would take more than a minute to disconnect or completely lock up the computer.  I'd have to restart Windows before I could dial-up again.  Then same problem,

Yes, I've tried updating drivers on all three but nothing seems to be able to give me one reliable modem.  

I know it's possible, but what are the chance of having three bad modems?

I've tried the modems in differrent PCI slots.

I don't have any IRQ conflicts (currently on 18 by itself).

I've updated the system BIOS.

I booted into safe mode and there are several more items under Network Adapters:

Direct Parallel
Realtek RTL8139 Family PCI Fast Ethernet NIC - Packet Scheduler Miniport
Realtek RTL8139/810X Family PCI Fast Ethernet NIC
WAN Miniport (IP)
WAN Miniport (IP) - Packet Scheduler Miniport
WAN Miniport (L2TP)
WAN Miniport (PPPOE)
WAN Miniport (PPTP)

Are these all necessary.

Thanks for your help.



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Greetings, schvankus!
  Check for line noise or problem with your ISP.  Internal modems are susceptible to noise. Make sure nothing else is hanging on the modem connection. Remove answering machine, fax machine, and lightening protection.  Use another telephone plugin to the wall.

Check if your ISP permit usage of your type of modem.  Did they change anything recently.

Best wishes, war1
Can you try a different ISP?
Can you try a different ISP?
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schvankusAuthor Commented:
My main computer is connected to the same phone jack and same isp and works fine.  I thought it might be the isp causing the disconnects or lack of data movement, but that's not the case.  Also,  I don't believe the ISP would cause the modem to lock-up the pc.

I work on computers all the time and have a dedicated phone cable I use for testing.  I know it works on other computers.


Hi schvankus,

First off, it seems to me that all three modems you have are SOFT modems which are HSP(Host Signal Processing) based, instead of being HARD ones(more DSP based.)  And the first two are made by the same manufacturer - Pragmatic, right?
Therefore they may not be so "completely different" due to the intrinsic nature of likely driver/comm-port conflict among common SOFT/HSP/Win modems.

Secondly, how do you use the three of them?  Are you binding them together using Multilink function or dial them seperately to different ISPs or for different Apps?  How many phone lines are you using at THE SAME TIME?

I suggest you set them up one by one first.  Then add another, then the third.  So it can be judged progressively to eliminate likely conflicts among drivers, comm ports or IRQs.

The reason you have to reboot to reset the modem connection is that Windows OS seems to "cache" the previous state of problematic connection and keeps it locked up until you reset it the "hard way"-reboot.

And your description of IRQ 18 is a bit ambigous - what are the comm ports and IRQs the three of them used - such as comm3, 4, 5; IRQ8, 10, 18, etc.?

Finally, when you qurry them, under "Driver details", did you see any of them share the same driver file name?  Also are any of the network adapters using the same comm port?  Chance of these conflict are slim since you said you could dial them seperately without problem.  Therefore the possibility of having all of them bad in your case is NIL.

Most likely the problem is SOFT, i.e., driver conflicts when you try to bind them together.  On the other hand, if your ISP does not support Multilink, you will likely be timed out or denied connection up front.

Let us know more details and how it progress.

schvankusAuthor Commented:
eXPaine:  sorry mate, maybe I didn't explain clearly.  I'm only using one modem at a time but have tried three different ones and all show similar problems.

The modem is currently on COM3 IRQ18.

I see what you say about Windows caching "the previous state of problematic connection and keeps it locked up until you reset it the "hard way"-reboot."  That makes sense.  



Well, that eliminated 2 out of 3 cans of likely SOFT-modem worms(g)

Can you "borrow" a HARD modem(one with a dedicated DSP chip set) or an external one to run the test?  If you can and it works fine, then that would further eliminate the likelihood of problematic link to your OS or BIOS setup.

Now you may pay more attention to the flow control part of the setup, e.g., try reducing the "Max Speed" in Modem Properties from 115200 progressively, or switching On/Off Hardware flow control, etc.

Also, try to disable your NIC by simply click the "Disable" button.
But I don't think the NIC is the winky link.  I notice you also have setup "Direct Parallel" link, is that right.  Just temp. disable all that.

BTW, I have never been able to figure out how to clear the network related cache in Windows, such as the one we mentioned and the "Repair" feature related to LAN/Eithernet cards.  If anyone has any tip on that, I'd greatly apprecate it.

See how it goes from there.


>"The modem is currently on COM3 IRQ18."

IRQ18 ????

A PC only has IRQs 0-15. How do you get IRQ18????
schvankusAuthor Commented:

as i understand it,  when APIC (Advanced Programmable Interrupt Controller) is enabled, IRQs are expanded to 24.

could this be a source of my problem?

i'm thinking of reinstalling xp with a different modem in it just in case something got screwed up with the first install.


I don't think your IRQ setting is the problem.  It's quite common nowadays that PCI cards use IRQ#s over 15, especially under later version of OS, in order to leave some room for backward compatibility for older cards such as ISA ones.

If you haven't gone too far installing other Apps, restalling XP may be a clean-cut way to go.  But before resorting to that, have you tried restoring XP to pre-problematic state, like before you tried to install those modems?  Or rolling back drivers within modem properties?

I was wondering the order you installed those three - which one had shown you the problem first?  Did you install one first, without realizing there might be connection problem before hand , then immediately tried to test another one?  Doing so without uninstalling the previous one first?  The reason I ask this is because you do have two that made by the same manufacturer - Pragmatic, even though they are made of different chipsets.  I have had nightwarish experiences installing modems from same brands/models/manufacturers, one after another or multiple at the same time in the same system.  They may be all competing for the same resources, even they have different .INF settings.

Another aspect about uninstalling modem - keep in mind that sometimes even you uninstall them "successfully" as indicated by the Control Panel setting or App Remove/Add, some left-over driver files or Registry entries can still mess you up.  That's the most difficult part of dealing with Soft modem installation.

Bottomline - if you want to avoid reinstall the whole OS, try all you can to uninstall and completely delete all modem drivers, related INF files, etc.  Keep copies of you Registry.  Or create restore point for XP before you do that.  Then try them one by one, make sure one works to your satisfaction before you plug in and test another.

Best of luck.

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Internal Modems have a problem in some areas for disconnecting. With my ISP, I had to change from Internal to External.

The second thing may be that your computer has some virus/dialer that is dialing to another phone number.

The best thing I can suggest is if you have some sort of thing to back your software up or have the System Restore feature, either restore your computer to before you had a problem, or simply re-format the computer.


PS. You may have to take the modems off to reactivate Windows XP Professional again. Everytime I have to format, I have to rebuild my system again...
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