Troubleshooting Unreliable Modem Connections
When a successful dial-up connection is
unexpectedly interrupted, Apple Remote Access responds:
"You have been disconnected."
And when similar circumstances prevent the connection from completing:
"The connection attempt failed. The activity log may have suggestions
for fixing problems."
If this becomes a recurring problem, use this troubleshooting path
to help identify solutions.
The occasional lost connection is to be expected given the nature
of the technology and the typical operating conditions. An unreliable
connection is suggested when disconnects occur more frequently,
often shortly after the connection has been established.
Note: Where Open Transport/PPP is installed, substitute "PPP
control panel" for "Remote Access control panel"
throughout the instructions that follow.
Step One: Check the idle timeout and protocol settings
If the disconnect always occurs after a specific interval of time,
or only after a period of network (Internet) inactivity, the problem
may be related to either the "disconnect if idle" setting
of Remote Access or the idle timeout policy of the Internet Service
a. Open the Remote Access control panel, click the Options
button, then click the Connection tab (see Figure 1). Click the
"disconnect if idle" checkbox to disable it if necessary,
or enter a larger number. Most ISP's will terminate the connection
after similar periods of idleness. Check with your ISP for specifics.
b. Click the Protocol tab. It should be set correctly for
the type of connection in use (see Figure 2). Standard dial-up Internet
connections use the PPP protocol, not the Apple Remote Access Protocol
(ARAP). The hardware or software setups of some Internet Service
Providers may not permit connections when the protocol is set to
Step Two: Check for physical connection issues
If the disconnect can be encouraged by moving the modem or its associated
cables, check them for secure connections and signs of damage.
Try a different, known-good telephone cable if available, then test
using a direct modem-to-outlet connection. If movement still breaks
the connection, seek service.
Step Three: Configure the Modem control panel
Configure the Modem control panel to use the modem script appropriate
for the modem. Apple-branded internal modems use these scripts,
Power Macintosh G3 (Blue & White)
PowerMac G3 Internal 56K, PowerMac G3 Int56K
PowerBook G3 Series
PowerBook G3 Internal 56K, PowerBook G3 Int56K
iMac Internal 56K, iMac Internal 56k (v.34
Power Macintosh G3 & Power Macintosh
PowerBook 3400 & PowerBook G3
PowerBook 3400/G3 Internal 33.6
Geoport Telecom Adapter (internal or external)
Step Four: Disable call waiting
When an ongoing modem connection is interrupted by a call waiting
tone signifying an incoming call, the modem will usually disconnect.
Disconnects related to call waiting are random and don't usually
occur only at precise intervals or always shortly after connecting.
If call waiting is enabled on the telephone line used by the modem,
open the Remote Access control panel and enter *70,, before the
telephone number (see Figure 4). The extra comma, signifying an
additional pause, is optional but occasionally necessary to allow
the command sufficient time to be acknowledged.
If your line requires pulse dialing, use 1170,, instead. Call waiting
will only be disabled for the duration of the connection.
Your local telephone company may require different numbers or may
not automatically provide this feature.
Step Five: Troubleshoot interoperability issues between modems
Where modems of different makes, models, firmware/flash-ROM revisions,
and chipsets are concerned, one modem may have an incompatible method
of implementing a connection that it has negotiated with the other
modem, or the negotiation itself may fail. For example, if a modem
cannot sustain the current connection speed but is unable to successfully
negotiate a slower connection with the other modem, the connection
will incur excessive transmission errors, decreasing throughput
and potentially forcing a disconnect.
a. If your modem can be flash-ROM upgraded via software,
apply the most recent modem update available. Apple 56K modem updates
are available online. The latest firmware code may make the two
modems more compatible--or less.
b. Disable 56K protocols in favor of V.34. Limiting the modem
in this way may reduce or eliminate the need for the modem to make
as many adjustments in response to poor line conditions, potentially
sidestepping interoperability issues altogether. This change is
incorporated into the "V.34 Only" modem scripts available
for some Apple 56K modems. A variety of other modem manufacturers
supply similar ARA modem scripts for their modems. If you are connecting
to the internet using software that does not use modem scripts,
supply the software with a V.34 initialization string appropriate
for your modem. Your ISP may be able to assist you, or you can teach
yourself the proper initialization string by studying the AT command
guide provided with your modem or available online from the manufacturer.
c. Ask your ISP whether different modems are available via
an alternate dial-in number, or switch to an ISP that provides different
modems (call them first, as they may already know of issues they
are having supporting the modem you are using). Perhaps borrow a
friend's Internet account, obtain a trial membership with another
ISP, or connect to a PPP test server if you know of one.
If all else fails, you may wish to go so far as to try a different
modem yourself--one that your ISP recommends for best compatibility.
Step Six: Reduce signal interference & distortion
The telephone network path between modems must be sufficiently free
of noise and frequency distortion to permit a stable connection.
The modem analyzes these line impairments as they affect the quality
of the transmission signal. Poor signal quality causes transmission
errors, reduced throughput, reduced connection speed, and dropped
a. Experiment with eliminating potential sources of line
impairments in the home:
- Any device connected
to any telephone outlet, especially if used by the modem, and
even if on a different line: telephones, including cordless
telephones and their base stations, answering machines, fax
machines, caller ID boxes, and other modems
- Telephone line splitters,
cable extenders, faulty or overly long telephone cables (shorter
- Surge protectors, including
those that offer telephone line protection
- Alarm systems, especially
those that are connected to the telephone system
- Computer equipment, including
- Fluorescent light fixtures
and light dimmers
- Satellite dish receivers
- Appliances such as air
conditioners, refrigerators, dryers, microwave ovens, and televisions
- Any AC power source and
- All other things electrical,
including problems with the premises wiring: loose or corroded
connections, too many splices or bridges, insulation deterioration
and exposed wiring, non-twisted pair telephone wiring
Start with a direct, unobstructed, modem-to-outlet connection using
a short, high-quality telephone cable. As a way of confirming the
problem prior to isolating it any further, there is the option of
testing with a direct connection to the external telephone box located
at the back or side walls of the residence. It provides one or more
standard telephone jacks supplying the home telephone connections
but bypassing most impairments inside.
b. Listen for noise. Because the telephone company is only
obligated to provide voice-quality phone lines, it is unlikely to
address the many and varied off-premises sources of line impairments
that can affect the connection but don't cause audible noise. Connect
a telephone to the wall jack used by the modem, then pick up the
line, dial the number 1 to stop the dial tone, and listen. Contact
the telephone company if the line is not quiet (loud hiss, pops,
static, voices), but first disconnect other telephone devices and
c. Use a local dial-in number to your Internet Service Provider.
Long distance and 800 numbers aren't typically a concern, but may
cause the call to be routed through more facilities, indirect paths,
and different carriers with different types of equipment and lines.
Local calls may be auto-forwarded in the same manner, but most reputable
ISP's don't engage in this practice.
If daunted by these varied and uncertain possibilities, consider
carrying the computer to a local Apple service provider for testing
on analog lines of confirmed quality.
Step Seven: Configure the Extensions Manager control panel for
Mac OS All
Realistically, these last two steps are unlikely to address this
particular kind of problem. Nevertheless, the possibility that extensions
troubleshooting or clean installing will resolve is one that cannot
be discounted, so be sure to try these if all else fails.
a. Open the Extensions Manager control panel and select whichever
Mac OS All set is available from the Selected Set menu (see Figure
5). For example: Mac OS 8.6 All, iMac All, and so on.
b. If the modem requires any of its own extensions (excluding
fax or telephony extensions), ensure they are installed and enabled.
Enabled extensions show an "x" in the adjacent checkbox.
Extensions Manager will ask to duplicate the Mac OS All set before
additional extensions can be enabled. Allow it to do so.
Of the modems that shipped with Apple computers, the following require
the extensions listed in order to respond:
Apple 56K modem
(but not Apple/GV 56K modem)
iMac Modem Extension, PowerMac G3 Modem,
or PowerBook G3 Series Modem, depending upon the computer
Geoport Telecom Adapter
Apple Telecom Modem, Express Modem Tool,
Geoport for Power Macintosh, Geoport Telecom Adapter, Geoport
Serial Driver, Serial Extension (PM 6100/7100/8100 only),
Shared Library Manager, Shared Library Manager PPC, and the
Express Modem control panel
PowerBook 3400/G3 Internal Modem/Ethernet
PowerBook 3400 Ethernet extension and PowerBook
3400 Modem extension, or just the PowerBook 3400/G3 Modem
c. Close Extensions Manager and restart the computer. If
the symptom does not recur, perform extensions troubleshooting to
isolate the problem extensions. It may only be necessary to correctly
configure the software that used them.
Step Eight: Perform a Clean Install or Clean Restore
The Mac OS may be damaged. Perform a clean install or clean restore
of the operating system. If there is any connectivity software or
modem software to be installed separately, do so immediately afterward.
If the problem continues, there is likely a hardware problem requiring