8.3 Receiving NO CARRIER message
There are some common cases when modem answers NO CARRIER:
If a data/voice/fax connection cannot be established
Right after hanging up the data/voice/fax connection
If there is no connection with a network – check antenna and registration status
(see Network registration)
If there is no power supply (see Power supply)
If modem answers NO CARRIER in some cases, you can have extended error code
using AT+CEER. The table below shows some of the codes which may appear.
Error code
1
Unassigned or unallocated number
3
No route to destination
6
Channel unacceptable
8
Operator determined barring
16
Normal call clearing
17
User busy
18
No user responding
19
User alerting, no answer
21
Call rejected
22
Number changed
27
Destination out of order
28
Invalid number format (incomplete number)
34
No circuit/channel available
38
Network out of order
Temporary failure
41
For further information about AT commands and their usage, refer to [1].
23
Description