IBM Aptiva Series Handbook page 150

Table 10: AT commands (Continued)
Command Function
Read S register r, where r=0-95
Set S register r to value n (r=0-95; n=0-255)
Tone dial
Numeric responses
Text responses
Hayes Smartmodem 300 compatible responses/blind dialing
Same as X0 plus all CONNECT responses/blind dialing
Same as X1 plus dial tone detection
Same as X1 plus busy signal detection/blind dialing
All responses and dial tone and busy signal detection
Reset and recall user profile
B-8 Appendix B: Modem information