GSM/GPRS device not functioning with a specific SIM

When a Multi-Tech GSM/GPRS device is found to not function with a specific SIM review the information below.

If the information below does not assist in determining the cause of the problem create a support case and indicate the outcome of all the suggestions below.

1. At same identical location if a different SIM from same carrier or SIM from another carrier is put into the same device is the device functional?

If a different type of SIM is put into same device at same location and device works the problem may relate to an interaction with the SIM, the network, and the device.

If a different type of SIM is put into the same device at same location and device still does not work this isolates issue to possibly be related to signal, band setting, SIM lock, or lack of registration.

2. Result of AT+CPIN?

The response should indicate "ready." If any other value is returned than ready refer to the AT command guide for your radio to determine the meaning of the +CPIN response.

3. Result of AT+CSQ

The first value of the response should indicate a value of 0-31 if signal is detected. A response of 99 indicates no signal. Ideally signal should be between 10-31.

If there is no signal verify
A. The correct antenna is being used
B. Verify the antenna is correctly connected.
C. Check

4. Result of AT+CREG?

Verify the device is registered. The second value in +CREG response should indicate either a 1 or a 5 if the device is registered to the network. If the first value is not 1 or 5 the device is not registered on the network. This could be an indication of weak signal, lack of GSM/GPRS signal, SIM lock, or incorrect band setting of radio.

5. Result of AT+WMBS?

Verify device is set for the frequency which is compatible with the local cellular network
+WMBS: 4,0 850/1900
+WMBS: 5,0 900/1800

Coverage maps for different countries and carriers can be researched on this website

To set correct value for your area issue one of the following commands

6. If the SIM is brand new and has never been inserted into any cellular device: What occurs when SIM is inserted into another GSM/GPRS device which functions with SIM, and then SIM is inserted back into the Multi-tech device? Does issue still exist?

In rare cases with certain carriers the use of a SIM for the first time in some GSM/GPRS devices may not result in proper registration/activation of the SIM on the network. In these cases putting the SIM into a different device will result in the SIM becoming "active" allowing SIM to correctly function in the GSM/GPRS device which previously had issue.

7. What occurs at same location if SIM with issue is put into a different brand/model of cellular device which is also only capable of 2G GSM/GPRS connections (device MUST NOT be capable of EDGE/HSPA/GPRS?)

If SIM does not work in another GSM/GPRS device at same location it is indication the issue may relate to lack of signal, lack of registration, SIM lock, or possibly the SIM is a 3G only SIM and not capable of 2G GSM/GPRS connections.

If SIM works in another GSM/GPRS device at same location it rules out the issue being related to use of a 3G only SIM.

8. Relating to #7: Research the specific brand and model of cellular device which the SIM can be inserted into and function normally. Verify the device is a 2G GSM/GPRS device only similar to the device with issue.

If the device which functions is capable of 3G, the issue may be the SIM is a "3G only" SIM and only capable of interacting with 3G devices.

7. Verify with the SIM carrier the SIM is not locked to a specific cellular device, or series of cellular devices?

8. Verify with the carrier the SIM is not a "3G" only SIM and verify SIM is capable of functioning in GSM/GPRS only cellular devices.

9. Verify with the carrier there are valid home or roaming partner 2G GSM/GPRS networks available at the location where modem has issue.

The issue may be lack of GSM/GPRS networks in the area, or there may be GSM/GPRS networks in the area however the SIM carrier has no roaming agreements with the carriers.

10. If still having issues after reviewing the above supply information to Multi-tech support ( ) as to the outcome of the above troubleshooting steps and provide a picture of both sides of the SIM which is having issue.