DirecTV DIRECT TV Manual page 101

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This setting is off by default. When
is on, the Receiver can determine whether the phone line is in use by
detecting voltage on the line. This allows it to avoid disrupting a call in progress (such
as another modem call).
However, if you are experiencing "Failed, Line unavailable" errors, or if the Receiver
is not making daily calls, you may have a low-voltage phone system that the Receiver
cannot detect. In this case, try selecting "Off" for .
With turned off, the Receiver must pick up the line to check
for a dial tone. If you are on the phone when the Receiver tries to call, you may hear a
click on the line. If you have another modem call in progress (on your computer or
other device), that call may be disrupted if the Receiver attempts to make a service
call.
If you turn off and you have a standard dial-tone, turn on
(described next).
This setting is on by default. If you leave it on, the Receiver
will check for a dial tone before it starts dialing. However, if you have a non-standard
dial tone (for example, an analog PBX system), or a stuttering dial tone (as some voice


messaging systems have), the Receiver will be unable to detect the dial tone and will
not make its daily call. If you have a stuttering or non-standard dial-tone, you may
want to turn this setting off to ensure that the Receiver can complete its daily calls.
When you select this option, the Receiver makes a short
phone call. This call is usually made to confirm that the current phone settings will
work properly. If the test is successful, press SELECT to continue. If the test is not
successful, you may have to change some phone dialing options; see "Phone
Troubleshooting," described on page 92.