User`s manual

U.S. Robotics I-modem Command Reference
Handshaking, Error Control, Data Compression, and Throughput • Page 11-7
connection. If the remote analog device does not have V.FC capability, the I-modem lis-
tens to the deviceÕs answer tones to identify what standard rate the remote analog device is
operating at, and then adjusts to that rate.
When the I-modem answers a call from an analog device, the I-modem sends out a series
of answer tone signals until both devices negotiate the best connection rate.
USR V.32terbo to USR V.32terbo
On these analog connections, I-modems have two features that result in outstanding per-
formance: Quick Connect and Adaptive Speed Leveling (ASL).
Quick Connect allows the devices to connect in approximately 7 seconds, a far shorter
time than with most devices.
ASL (described below in Other V.Protocols) is used by I-modems operating in V.32terbo
and V.32bis modes.
Other V. Protocols
Earlier, lower-speed ÒV.Ó protocols do not employ line probing. Instead they use pre-
deÞned answer tones to specify or identify speed capabilities. These protocols deÞne the
following maximum speeds: