User`s manual

U.S. Robotics I-modem Command Reference
Handshaking, Error Control, Data Compression, and Throughput • Page 11-4
By default, the I-modem tries to establish a multilink PPP (MP-PPP) session. You can set
up the I-modem to skip either the 64 Kbps or the 56 Kbps call. To skip the 64 Kbps call,
set S67.1=1.2=0. To skip the 56 Kbps call, set S67.1=1.2=1.
You can change whether the I-modem makes one or two calls by a combination of bit 3, S-
register 68 and the use of an ampersand (&) in the dial string, as shown in Table 11-1.
You can disable TurboPPP by turning on bit 2 of S-Register 68 (send ATS68.2=1
<Enter>). When TurboPPP is disabled, the I-modem performs asynchronous
PPP to syn-
chronous PPP conversion, but uses only one B-channel with no compression.
Clear-Channel Synchronous (External I-modems Only)
The I-modem sets up a clear channel (64 or 56 Kbps) with a remote device. Common
applications are videoconferencing and remote access to mini- or mainframe computers.
For more details, see Chapter 16,
Analog Synchronous Applications.
Number of calls made
Dial string S68.3=0 S68.3=1
ATDT5550001 2 1
ATDT5550001& 2 2
ATDT5550001&5550002 2 2