COURIER HIGH SPEED MODEMS
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⎯Bn, &Gn, &Pn. Bn is described earlier in this chapter.
&Gn 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. |
