User's Manual Part 1

58 AT Commands
Revision 1.8 P/N 90023363
Response: If there is no dial tone, the modem will return the string:
NO DIALTONE
where the command ATX has been set to 2 or 4.
If there is an error and it is related to the mobile equipment’s (ME)
functionality, the modem will return the string:
+CME ERROR: <error>
If the connection is busy, the modem will return the string:
BUSY
where the command ATX has been set to 3 or 4.
If the connection cannot be established, the modem will return the string:
NO CARRIER
If the connection is successful and is non-voice call, the modem switches
to data state and the modem will return the string:
CONNECT<text>
where <text> is only displayed if the command ATX has been set to a value
greater than 0.
If connection successful and is a voice call, the modem will return the
string:
OK
When the modem releases the call and returns to command mode, it
returns the string:
OK
Example:
ATD2<cr>