error code, if Response = N
01 Checksum error
02 Syntax error
03 Operation not supported by system
04 Operation not allowed (at this point in time)
05 Call barring active
06 AdC invalid
07 Authentication failure
08 Legitimisation code for all calls, failure
09 GA not valid
10 Repetition not allowed
11 Legitimisation code for repetition, failure
12 Priority call not allowed
13 Legitimisation code for priority call, failure
14 Urgent message not allowed
15 Legitimisation code for urgent message, failure
16 Reverse charging not allowed
17 Legitimisation code for reverse charging, failure
18 Deferred delivery not allowed
21 Standard text not valid
22 Time period not valid
23 Message type not supported by system
24 Message too long
26 Message type not valid for the pager type