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Troubleshooting "No Dial Tone"


When the modem cannot detect or successfully acquire a dial tone, the connection attempt will fail, and Apple Remote Access will respond:

Or, when using the bundled America Online 4.0:

Use the troubleshooting path in this article to help identify the source of the problem.

Note: While this article specifically mentions iMac, it is applicable to the PowerBook G3 Series (Bronze keyboard) and Power Macintosh G3 (Blue and White) as they use a variation of the iMac modem.


Before beginning, ensure that the modem hasn't been silenced, which wouldn't otherwise affect its functionality, but may be misleading. To confirm, and to prepare for the troubleshooting that follows, turn the computer volume up in the Control Strip or the Monitors & Sound control panel. Increasing the volume will automatically uncheck the "Mute" button in Monitors & Sound. If no system beep is heard, troubleshoot for a no computer sound problem first.

Troubleshooting Path

Between steps, close/quit any open control panel or application, saving changes as necessary.

Step 1

Verify Physical Connectivity

Check the telephone line connection at the wall outlet and the modem port. Ensure that it is not connected to the ethernet port by mistake. Push firmly in on the connectors at both ends, or disconnect and reconnect them, to seat them securely.

NOTE: This modem is incompatible with digital/PBX phone lines. If an ordinary, residential, consumer telephone has worked in the same outlet, it is a compatible analog line.

Step 2

Configure Modem Control Panel

Configure the Modem control panel as shown. Selecting the wrong modem script can cause this symptom. It doesn't matter whether modem firmware updates have been applied or the V.34 modem script selected.

Step 3

Configure Remote Access and Test

Open the Remote Access control panel. Enter a name (user ID), password, and telephone number.

Inaccurate entries will not prevent detection of a dial tone; however, if a prefix like "9" must be dialed to reach an outside line, enter it before the telephone number, followed by a comma as shown.

Click "Connect" and listen for a dial tone, number tones, or handshaking (squealing sound). If heard, or if the "Status" field ever shows "Starting PPP," "Starting network protocols," "Communicating at 24000 bps," or any other such indicator that appears after acquiring a dial tone, the problem is fixed.

If it is convenient to perform step 12 (test the line with a telephone), do so now; otherwise, proceed through the steps in order.

This step is repeated in steps 5, 7, 9, 11, 13, and 14.

Step 4

Configure Extensions Manager For Mac OS Only

Open the Extensions Manager control panel. Select "iMac All" or "Mac OS 8.5 All" from the pop-up menu shown. Future Mac OS revisions will introduce other name or version changes but the correct "All" choice should be clear.

Ensure that iMac Modem Extension is among the enabled extensions listed (enabled extensions show an "x" in the adjacent checkbox).

Close Extensions Manager and restart the computer. Any extensions that might have captured the modem for their own use (commonly fax or telephony extensions) are now disabled and will remain so until enabled in Extensions Manager again.

Step 5


Open the Remote Access control panel. Click "Connect" as in step 3. Watch and listen.

If it's fixed, the offending extensions can be further isolated via extensions troubleshooting and, if necessary, proper configuration of the software that used those extensions.

Step 6

Disable Dial Tone Checking

Open the Modem control panel. Click the "Ignore dial tone" checkbox to enable it. Remote Access will no longer check for a dial tone before dialing out, proceeding instead as if one is present.

Step 7


Open the Remote Access control panel. Click "Connect" as in step 3. Watch and listen.

IMPORTANT: Because "Ignore dial tone" is enabled, it's possible that only the number tones will be heard as dialing occurs, but not the initial dial tone or modem handshaking. Typically, the "modem is not responding properly" alert will then appear. If so, the problem persists.

If it's fixed, the problem was due to the unique characteristics (volume or frequency, for example) of this dial tone as delivered through the analog line. There are three options:

    • Leave "Ignore dial tone" enabled.
    • Experiment with cleaning up the telephone signal by hardware-isolating the telephone line as per step 13.
    • Call the telephone company to have them check the lines, though they may already be as clean as they're realistically going to get.

Finally, disabling dial tone checking will usually work around the problem posed by some voice mail services that notify the user of waiting mail by altering the dial tone or inserting a series of tones before it.

Step 8

Reset Parameter RAM

Though the fax, telephony, and other 3rd party extensions were disabled in Extensions Manager, certain Chooser settings they might have established could still reside in PRAM.

Reset the Parameter RAM: shut the computer down, then power it on and immediately press "Option-Command-P-R" (four keyboard keys, all pressed together), keeping them pressed until the computer startup chime repeats at least once after the initial chime.

Step 9


Open the Remote Access control panel. Click "Connect" as in step 3. Watch and listen.

If it's fixed, the problem was a conflicting setting in Parameter RAM, probably created by one or more of the disabled extensions, either because it was involved in a system crash, is in conflict with other extensions or with the Mac OS, or was not configured correctly. Perform extensions troubleshooting, but keep in mind that the problem may not immediately (or ever) return, even after turning 3rd party extensions back on.

Step 10

Perform AT Command Troubleshooting

AT command troubleshooting speaks more directly to the modem using a terminal emulator and the Serial comm-toolbox tool. By bypassing Remote Access, it addresses the possibility that Remote Access has become damaged.

There are a variety of shareware and commercial terminal emulators available, any of which would suffice, but the following steps will make use of software bundled with the iMac.

Open AppleWorks or ClarisWorks (different names for the same program), select a Communications document, and click "OK." If an alert says that no terminal tools are available, reinstall the program from the iMac Install CD.

A blank, untitled communications document (terminal window) should now appear. Choose "Connection" from the Settings menu to open the Connection Settings window.

Choose "Serial Tool" from the "Method" pop-up menu. The other settings should be correct by default, but ensure that "Internal Modem" is selected. Click "OK."

Choose "Open Connection" from the Session menu:

Now proceed as shown below. Enter AT&F, ATDT, and ATDT [telephone number].

Note the clock in the upper-left corner of the document window: it must be advancing. If it is not advancing:

    • Repeat the previous AppleWorks steps, starting with the Settings menu.
    • Quit and restart AppleWorks, then repeat the previous AppleWorks steps.
    • Reinstall AppleWorks.
    • Skip to step 12 and continue down from there.

Important: If the clock is advancing and no characters appear in the terminal window as you type, the computer can't see the modem at all. This can mean:

    • Another application or extension is using the modem. If the previous troubleshooting steps were correctly followed, this possibility has been eliminated.
    • The modem is dead, unseated from its internal socket, or some other internal hardware failure has occurred. This conclusion cannot be drawn until all the software possibilities are exhausted. There's only one left:
    • The system software is corrupt.

Read these 3 options carefully, then choose one:

    • If a dial tone was acquired using AT commands, proceed to the next step.
    • If characters could be entered but no dial tone was acquired, skip to step 12 now.
    • If no characters could be entered in the terminal window, skip to step 14 now.

Step 11

Trash Preferences

Because AppleWorks can obtain a dial tone but Remote Access cannot, locate and trash "Modem Preferences" and "Remote Access Connections," located as follows:

    • System Folder : Preferences : Modem Preferences
    • System Folder : Preferences : Remote Access : Remote Access Connections

Then repeat steps 2 and 3. If it still doesn't work, it could be argued that the Remote Access components alone have become corrupted and require reinstallation, but because they have thus far allowed themselves to be opened and configured, performing step 14 now is preferred.

Step 12

Verify Cable & Outlet

Disconnect the telephone cable from the modem and plug it into a telephone, then listen for a dial tone with the telephone receiver. If a dial tone cannot be heard, there is a problem with the outlet or the cable. Try a different cable and outlet.

IMPORTANT: It doesn't matter that a telephone used to work on the wall outlet at some time in the distant past, or that it worked there while using a different telephone cable. Unless the outlet and the cable were tested with a telephone just prior to connecting the iMac to the same cable and same outlet, this must now be done.

Arriving directly from step 3? Go back.

Step 13

Hardware-isolate Line

Establish a point-to-point, single-cable connection between the modem and the wall outlet, isolating the line from all other devices, including telephones, answering machines, fax machines, and even caller-ID boxes, cable extenders, and line splitters (pictured). Thus, the configuration should be: iMac modem > telephone cable > wall outlet. The shorter the telephone cable, the better. Then retest as per step 3, using the Remote Access control panel.

If that works, one or more of the removed devices was hurting the line quality (thus affecting the dial tone) or pushing an already poor line past the breaking point. There's not much that can be done except attach those devices to different outlets or experiment with other devices, cables, splitters, and combinations thereof. Sometimes the inside or outside home wiring is at fault, requiring an experienced telephone technician to diagnose.

Remove any splitters and other devices and connect directly to the wall outlet.

Step 14

Clean Installation

Perform a clean installation of the operating system. Instead of manually disabling the existing System Folder, start up from the Apple Restore CD. Then use Apple Software Restore, confiqured at its default settings to perform a clean installation.

Then repeat steps 1 & 2 to retest. If the problem is fixed, you are done.

If the problem continues, the iMac will probably need service. But first, you may wish to re-enable the old System Folder:

1. Start up from one of the two orange system CDs.
2. Drag the System Folder at the root level of the hard drive to the Trash (the whole folder).
3. Open the "Original Items" folder at the root level of the hard drive. Locate the System Folder within and drag it on top of the hard drive icon, replacing the one just moved to the trash. Then open and close the System Folder to ensure it becomes blessed. A blessed System Folder is represented by the happy Macintosh icon superimposed on the System Folder icon. Restart, and manually eject the system CD after the startup chime.
4. The "Original Items" folder still retains all of the applications that originally shipped with the computer. Each will have a freshly installed duplicate outside of the "Original Items" folder. Either the duplicates or the originals may be removed, but be careful not to throw away any of your own documents or other items that might have been saved to any of those locations.



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