First aid for signal strength

1. Sim card pin

Suddenly the SMS Gateway stops sending text messages and does not receive a signal anymore. The configuration and the location of the SMS Gateway did not have changed. The common issue is a configured pin on the sim card.

To exclude possible issues with the pin you have to remove it from the sim card and the configuration of the SMS Gateway.

2. Reboot and powerless

If the SMS Gateway already have issues with the connectivity during the inital configuration you should halt the SMS Gateway and remove the power from it. This step should be done after a sim card switch or similar proceedures to exclude issues with already set data on the modem.

3. Location

The signal strength is correlated with the location of the SMS Gateway. If there is no signal the SMS Gateway can not connect to the mobile stations.

Factor	possible issues
Antenna	the used antenna can make a huge difference.
Cell tower	blocked cell towers by the landscape.
Facility	the signal strength in a room can differ a lot based on the walls.
Provider	the signal strength can differ for a different provider.
Weather	the weather can change the singal strength too.

4. Fluctuating signal

The modem of the SMS Gateway switches automatically between 3G and 4G. In some cases the switch can be an issue. Not every sim card is activated for 4G which will disturb the text message delivery. To determine if your sim card supports 4G you have to ask your provider.

5. Modem issues

To figure out if there are issues with the modem you can check the support lof of the SMS Gateway.

You can download the support log of your SMS Gateway in the web interface under Help - Support.

Open the received file with a archive tool. You can find the log of the modem under var/log/smsd.log.

You can open the file with notepad++ or similar.

The log can contain certain error messages:

Log entry	Issue	Solution
GSM0: CMD: AT+CPIN?: +CME ERROR: 10 (SIM not inserted)	The sim card is not inserted or can not be regonized by the modem	Insert a functioning sim card
GSM0: Couldn't open serial port /dev/gsm0, error: No such file or directory, waiting 30 sec.	During the initialisation the connection to the modem will be resetted. You can ignore this message if it shows only once. If this message occurs more often there could be a issue with the connection between the modem and the SMS Gateway	For the Rack Editions you can check the modem LEDs: Modem Status Otherwise contact our Support
GSM0: The modem answer was not OK: +CMS Error: 350	CMS Error 350 is a catch all error message which can have a lot of meanings	The most common errors are listed here: CMS Error 350