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modem - "cannot open port"

gardanzo asked
Medium Priority
Last Modified: 2013-12-16
I'm installing Win95 on a new multimedia system with a network.  All is well, except I can't open the port to my modem.

At first I tried it with the internal modem that came with the pc.  Com2 was disabled at the bios, and Win95 correctly setup Com2 from the modem.  The settings all checked out.  When clicking on a modem connection I receive "dial up networking or another program is accessing your modem."  

Next, I uninstalled the internal modem and installed my old external modem to Com2, with Com2 enabled at the bios.  Same problem.

Then I changed Com2 to Com4, same problem.  

I've checked the register and ini files and don't see anything unusual.

I've lots of hours in this installation and setup, and I don't want to reinstall if I can avoid it.
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Now assuming that you modem is set properly thsi documentation might be helpful if not I would wanna try few things if what I posting now does not help O.K.??
When you attempt to start a communications program, you may receive one of the following error messages:

•Error: port in use •OpenComm: Port already open


This behavior can occur if Rnaapp.exe is active in memory.


To work around this issue, follow these steps:

1.Press CTRL+ALT+DELETE to open the Close Program dialog box.

2.Click Rnaapp to select it, and then click End Task.

3.Start your communications program.


When you finish using a communications program and close the connection, Rnaapp.exe is still running and the port remains unavailable to non-TAPI programs.

Rnaapp.exe is left in memory to allow TAPI programs to open faster. Rnaapp.exe is eventually unloaded from memory (unless Dial-Up Networking Server is set to allow caller access), but it may take 10-15 minutes.
I would like to guide you an a few check points to verufy is

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if your modem is configured properly, keep me posted


I've got my old and new computers setup side by side.  In the old (works fine) one, when I click on the dial-up icon (picture of a telephone - makes a dial-up connection to my ISP) everything works fine.  Clicking on Ctrl-Alt-Del shows that rnaapp is not running.

Now, on the new computer, I do the same thing.  I check to see that rnaapp is not running, which it's not.  After clicking on the dial-up icon (setup exactly the same as on the old computer) I get this message: "The modem is being used by another Dial-up Networking connection or another program. Disconnect the other connection or close the program, and then try again."  I then check and note that rnaapp *is* now running.

So RNAAPP does appear to be the problem, but what do I do now? How do I prevent it from loading automatically?


Another symptom: If I go to control panel / modems / diagnostics, when I click on More Info I get " Couldn't open port."  All the settings of the port and modem appear correct.  After performing this task, RNAAPP is *not* running.


I got it!  I searched some of the PAQs here and found some other instances of the same problem.  Here was a suggestion from another expert:

Answer from wwillis...

Boot "safe mode command prompt only" and see if you can echo the com port the modem is on. If it is on com1 for instance you would type:
echo ata > com1
if the modem is responding correctly at that point it should go offhook and start making the handshaking noises. If it does type: echo ath > com1 which will hang it up. If that doesn't work you are having a problem with the modem that exists at the BIOS level (may try disabling the serial ports in CMOS setup if it is an internal modem) or a hardware failure with the modem itself. If it does work then you know for sure it's a Windows problem. At that point cd \windows\system and type: ren telephon.cp$ telephon.cpl and hit enter, then type: tapiini ...this will recreate the telephon.ini file in case for some reason it got corrupted. reboot back into Windows and test the modem. if it works, great, it was probably telephon.ini ...if not go to control panel. You should now have an icon for Telephony after renaming the .cpl file. Go into telephony and make sure Unimodem service provider is listed first. Sometimes some 16-bit service provider (old versions of AOL or Compuserve can hose this) will put itself first and that will stop all 32-bit communication (DUN and hyperterminal). If Unimodem isn't first there is an option there to change the order (can't remember precisely what the button says) and that should fix it. Good luck!


I followed Will's advice and received no response from the echo.  I went to the cmos and swapped com1 and com2 and all of their settings, so that my mouse would be com2 and modem com1.  After restarting, the mouse wasn't found, there was something wrong with com2 and its settings.

I switched them back and this time changed the irq setting for com2 from 3 to 9, and voila!  It fixed the problem.  Apparently there was something wrong with irq3 at the system board/bios level; this is why neither the external nor the internal modem worked on irq3.

Thanks for your help experts :-)
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