Multi-Tech Systems MTCBA-G-U ユーザーズマニュアル

Chapter 4 – Troubleshooting and Frequently Asked Questions 

Multi-Tech Systems, Inc. MultiModem GPRS USB Wireless Modem User Guide 

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Before calling the Multi-Tech Technical Support, check to the following connections: 

• 

The right antenna is connected to the modem  

• 

The serial cable connection is correct 

• 

The power is connected correctly and the power lights on the modem are on 

• 

Verify your signal strength 

• 

Verify your network registration 

• 

Use the following situation examples to troubleshoot the modem not answering and the modem 
returning a No Carrier message. 

If the Wireless MultiModem does not answer through the serial link upon an attempted transmission of data or 
voice signals, see the table below for possible causes and solutions. 

Is the communication program 
properly configured? 

In communications program, verify that modem 
parameters have been set to the values shown here: 
Data bits = 8 
Parity = none 
Stop Bits = 1 
Baud = 115200 bps 

Is another program interfering 
with the communication 
program? 

Close any such application program. 

Is the modem set to 
autoanswer? 

Type ATS0=1  (to set to auto answer on the first ring) 
Type ATA  (to set to manual answer)  

(nothing) 

Is the communication program 
receiving RING responses? 

Type ATS0=1  (to set to auto answer on the first ring) 
Type ATA  (to set to manual answer)  

Solutions for “no carrier” message 

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######;