USRobotics V.34 User Manual

Page 67

COURIER HIGH SPEED MODEMS

4-30 Data Mode Operations

INQUIRY AND HELP

The modem displays information such as the current modem
settings, product code, and call duration. It also displays
summary information for every command that the modem
supports.

For more information on Inquiry and Help commands,
including sample displays, see Chapter 6.

TESTING

The modem can perform a number of tests including Analog
Loopback, Digital Loopback, and Remote Digital Loopback.
These tests can be used to check the operations of the modem's
transmitter and receiver, or to locate a problem with a remote
modem or telephone channel. Error control must be disabled
for these tests.

See Appendix H for more information.

INTERNATIONAL CALLS

There are three commands that apply to international calls
above 1200 bps



n, &Gn, &Pn. Bn is described earlier in this

chapter.

This setting applies only to overseas calls at 2400 or 1200 bps.
British phone switching systems require the modem to send an
1800 Hz guard tone after it sends an answer tone. Some other
European phone networks require a 550 Hz guard tone. Guard
tones are not used in the United States or Canada.

&G0 No guard tone. This is used in the U.S. and in Canada.

Default.

&G1 This sets a 550 Hz guard tone, and is used in some

European countries.

&G2 This sets an 1800 Hz guard tone, and is used in the U.K.

and some Commonwealth countries. &G2 requires the
B0 setting.