Troubleshooting "No Dial Tone"
Note: While this article specifically mentions iMac computers, it is equally applicable to the PowerBook G3 Series (Bronze keyboard) and Power Macintosh G3 (Blue and White) computers because they use a variation of the same modem.
When the modem cannot detect or successfully acquire a dial tone, the connection attempt fails, and Remote Access responds with this message:
Figure 1: ARA dialog
Or, when using America Online 4.0:
Figure 2: Connection warning
Use the troubleshooting path in this article to identify the source of the issue.
(If Open Transport/PPP is installed, substitute "PPP control panel" for "Remote Access control panel" throughout these instructions.)
Don't Confuse a No Dial Tone Error With a Silenced Modem
The audio feedback of some Apple internal modems, including those in iMac and Power Macintosh G3 (Blue and White) computers, is passed through the computer's speakers. If the speaker volume is turned off, you cannot hear if the modem is able to detect and acquire a dial tone.
Turn the computer volume up in the Sound Volume portion of the Control Strip, the Sound control panel, or the Monitors & Sound control panel. Increasing the volume automatically deselects Mute in the Sound, or Monitors & Sound control panel.
Figure 3: Control strip
Verify Physical Connectivity
a. Check the telephone line connection at the wall outlet and the modem. For computers with internal modems, ensure the line is not connected to the Ethernet port (if available) by mistake. Push firmly in on the connectors at both ends, or disconnect and reconnect them, to seat them securely.
Figure 5: Modem port
b. External modems provide an additional jack for connection to a telephone. Do not connect the line from the wall outlet to this jack, which is often identified by an icon of a telephone (see Figure 6).
Figure 6: Icon representing the wrong modem jack for a modem-to-wall connection
Note: Most analog modems do not work with digital/PBX phone lines. If an ordinary residential consumer telephone works in the same outlet, it is a compatible analog line.
Set Up the Modem Control Panel
Set up the Modem control panel to use the appropriate modem script. Apple internal modems use these scripts, by computer:
|Power Macintosh G3 (Blue and White)||PowerMac G3 Internal 56K, Power Mac G3 Int56K (v.34 Only)|
|PowerBook G3 Series||PowerBook G3 Internal 56K, PowerBook G3 Int56K (v.34 Only)|
|iMac||iMac Internal 56K, iMac Internal 56k (v.34 Only)|
|Power Macintosh G3||Apple/GV 56K|
|Power Macintosh 6500||Apple/GV 56K|
|PowerBook G3||PowerBook 3400/G3 Internal 33.6|
|PowerBook 3400||PowerBook 3400/G3 Internal 33.6|
|GeoPort Telecom Adapter (internal or external)||GeoPort/Express Modem|
Figure 7: Modem control panel
Configure the Remote Access Control Panel and Test
a. Open the Remote Access control panel. Enter a name (user ID), password, and telephone number.
Inaccurate entries do not prevent detection of a dial tone. However, if a prefix such as "9" must be dialed to reach an outside line, enter it before the telephone number, followed by a comma as shown in Figure 8.
Figure 8: Remote Access control panel
b. Click Connect and listen for a dial tone, number tones, or handshaking (squealing sound). If they are audible, or if the Status field shows "Starting PPP," "Starting network protocols," "Communicating at 24000 bps," or any other such indicator that appears after acquiring a dial tone, the issue is fixed.
c. If it is convenient to perform step 8 (test the line with a telephone), it may save some time to do so now. If it is not convenient, proceed through the steps in order.
Disable Dial Tone Checking and Try Again
If the dial tone does not conform to what the modem expects to hear (because of poor signal level or quality, or non-standard frequency, for example) it may be difficult for the modem to recognize a dial tone. In such cases the modem software can be configured to assume that a dial tone is present without first checking for it.
a. Open the Modem control panel and click "Ignore dial tone", then close the control panel and save the changes.
b. Open the Remote Access control panel and click Connect, as in step 4. Watch and listen.
Important: Because "Ignore dial tone" is selected, you may only hear the number tones as dialing occurs, and not the dial tone or modem handshaking. The "modem is not responding properly" alert may then appear. If so, the problem persists.
c. Voice mail. Disabling dial tone checking may work around the issue posed by some voice mail services that use an altered dial tone, or a series of initial tones, to notify the user of waiting voice mail. If a voice mail service is enabled on the line and the problem persists, try entering one or two commas (,) before the telephone number in the Remote Access control panel. Each comma represents a pause of a few seconds. The idea is to delay dialing until after the voice mail tones have ended. If this works, it may not be necessary to leave "Ignore dial tone" selected in the Modem control panel, though doing so does not affect modem performance.
Damaged Remote Access preferences may be at fault. Considering that Remote Access was able to successfully detect and initialize the modem prior to checking for the dial tone, the odds of this are very unlikely, but it is easy to confirm prior to the more time-consuming tasks ahead.
a. Move these two preference files to the desktop (or anywhere outside of the Preferences folder):
If you are using Apple Remote Access:
- System Folder : Preferences : Modem Preferences
- System Folder : Preferences : Remote Access : Remote Access Connections
If you are using Open Transport/PPP:
- System Folder : Preferences : Modem Preferences
- System Folder : Preferences : PPP Preferences
b. Repeat steps 3 and 4 to set up the control panels and test. If the symptom persists, the preferences were not at fault. To reclaim the configuration information they contained (optional), move them back to their original locations and allow them to replace the newer preference files that were created.
Hardware-Isolate the Line
Establish a point-to-point, one cable (the shorter the better) connection between the modem and the wall outlet, isolating the modem, the line, and the outlet from all other devices, including telephones, answering machines, fax machines, caller-ID boxes, cable extenders, line splitters, and so forth. Then retest as per step 4.
If that works, one or more of the removed devices was impairing the line quality (thus affecting the dial tone) or pushing an already poor line past the breaking point. It may be necessary to 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 a telephone technician to diagnose.
If possible, check the modem with Apple Hardware Test.
If the computer came with Apple Hardware Test (included with iMac (Summer 2000), Power Mac G4 (Gigabit Ethernet), Power Mac G4 Cube, or PowerBook (FireWire) computers), start up with the Apple Hardware Test CD-ROM disc and open the Quick and Extended tests. If the Apple Hardware Test detects a modem error, note the error code, and contact Apple or an Apple Authorized Service Provider.
Confirm That the Cable and Outlet Are Good
Disconnect the telephone cable from the modem (leave it attached to the wall outlet) and plug it into a telephone. Listen for a dial tone with the telephone handset. If it cannot be heard, there is a problem with the outlet or the cable. Try a different telephone cable and, if necessary, a different outlet.
It does not matter that a telephone used to work on the wall outlet at some earlier date, 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 modem to the same cable and same outlet, this must now be done.
Note: If you arrived at step 9 directly from step 4, continue troubleshooting at step 5.
Perform a Clean Installation or Clean Restore
The Mac OS may be unusable.
a. Perform a clean installation or clean restore of the operating system. If there is any connectivity software or modem drivers to be installed separately (GeoPort modems, for example, require the reinstallation of Apple Telecom), do so immediately afterward.
b. Repeat steps 3 and 4 to retest. If the problem continues, there may be a hardware issue with the modem.