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Chapter 3 – Troubleshooting
Multi-Tech Systems, Inc. MultiModem® GPRS with USB User Guide 32
Situation B: The modem always returns «No carrier» when trying to
issue a communication
Solutions for “no carrier” message
If the modem returns … Then ask … Action
no carrier
(esp. for data communication)
Is the selected
bearer type
supported by the
called party?
Is the selected
bearer type
supported by the
network?
Type AT+CEER to view the extended
error code (see “Error Results Codes"
in the AT Command guide).
Be sure that the selected bearer type
is supported by the called party.
Be sure that the selected bearer type
is supported by the network.
If no success, try bearer selection
type: AT+CBST=0,0,3
Be sure SIM card is available for
data/fax calls.
no carrier
(esp. for voice communication)
Be sure that the semicolon character
(“;”) is typed immediately after the
phone number in the AT command.
E.g., ATD######; type
AT+CBST=0,0,3
Configure the SIM card for data/fax
calls.
Is the received
signal strong
enough?
See “Verifying Signal Strength.”
Is the antenna
properly
connected?
See “Antenna/RF Specifications.”