IBM Aptiva Handbook page 152

The following table lists the basic codes that the modem sends to your computer in response to the commands you type. They
are called response codes.
Table 5: Basic Response codes
Digit code Word code
0 OK
1 Connect
2 Ring
3 No carrier
4 Error
6 No dial tone
7 Busy
8 No answer
11 Connect xxxx
24 Delayed
32
Blacklisted
33 Fax
35 Data
+F4 +FC error
B-12 Appendix B: Modem information
Meaning
Command was carried out without error
Connected at 300 bits per second (bps)
Ringing signal detected
Carrier is lost or not heard
Error in the command line
Invalid command
Command line exceeds buffer
Invalid character format
No dial tone during the time-out period
The line being called is busy
The line being called did not answer within the time-out period
Connected at 2400 bps
Dialing delayed
Number is blacklisted
Fax connection
Data connection
Fax error