The CompatibilityFlags entry directs Unimodem to lower DTR and to then wait 50 ms before closing the communications port.
A single command string.
HKR, ,CompatibilityFlags, 1, 01, 00, 00, 00
This command occupies a single bit. The remaining bits are reserved and should be set to 0. This command is rarely used and currently applies to only a few US Robotics Sportster modems.