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| Troubleshooting Modems | Operation and
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The modem responds with "NO DIALTONE" when I try to dial out
Explanation: When you try to dial the phone number for the remote host, the system
responds saying that there is no dial tone.
Diagnosis: This generally means that the connection of the modem to the phone
system in the building has been compromised, or there is a problem with the way the modem
is configured. It is usually something simple like an incorrectly connected phone cord or
something of that nature.
- Try a regular phone plugged into a different phone extension. If you don't hear a dial
tone, you have a problem with your phone line. Call your local phone company's repair
- Check the phone cord where it goes into the modem's phone jack and make sure it is
plugged into the correct one. Most modems have two jacks, right next to each other. One is
for connecting the modem to the phone system, and the other is a pass-through for
connecting a regular voice phone to the modem, for convenience (you can use the phone
through the jack to the modem, which lets you use either the modem or the phone handset
without requiring two wall jacks or a line splitter). The jack for connecting the input
phone signals to the modem is usually labeled on the modem as "Line" or
"Wall". If you plug the cord into the other jack by mistake (usually labeled
"Phone" or "Handset") then the modem will not be able to find a dial
tone to dial out.
- Make sure that the cord is not disconnected. Make sure the other end of the cord goes
into the wall jack properly. A simple test is to disconnect the phone cord from the modem
and plug it into a regular phone and see if you can hear the dial tone. If you cannot hear
it, but another phone jack in another room has a dial tone, there may be a wiring problem
with this particular jack.
- Make sure the speaker for the modem is turned on and listen carefully for any sign of
problems that you might be able to hear coming from the modem.
- Ensure that nobody else is using the line. If the modem goes off-hook to use the phone
and somebody else is already on it, it will report "NO DIALTONE".
- Some modems will report "NO DIALTONE" when they encounter a phone system
problem. For example, if you try to dial out and get a recording such as "All
circuits are busy now" then the modem may become confused. Usually this happens after
it succeeds in dialing out and it will return with "NO CARRIER" after a few
seconds of getting this message, but it may say "NO DIALTONE" as well. You can
usually hear when this is happening by listening to the modem speaker.
- Make sure that you are not trying to dial out on a digital PBX phone line. Many
companies today use digital phone systems; there are a number of outside "true"
phone lines that go to the phone system, but each extension is only being fed an internal
digital signal. Even when you dial "9" to get an outside line, you are hearing a
digital translation of what is on the actual analog phone line. Regular modems will not
work over a system like this unless a converter is used that is specifically designed to
allow this type of functionality.
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