Recently, I had a Samsung A13 automatically unlock from Straight Talk after the 60 activation period. The problem I was facing was that when inserting a different SIM card, I could only get a signal for SMS texts and calls. Data and MMS texting wasn’t working.
When going to Settings > Mobile Networks > APN, the ability to see or edit APN’s is missing. The reason for this I found out was because the CSC (country specific code) was set to TFN. Using the SamFw Tool, I was able to change it to a more open code like GSC. This CSC allows for adding, editing, and removing APN’s. This allows for inputting the correct settings to get data and full texting working.
The problem came specifically with the Samsung A13: every time I inserted the SIM card, the phone would restart and then change the CSC back to TFN to where I couldn’t edit the APN again.
As it turns out, there’s a service in the background in the Samsung A13 that forces the phone into restart that you can disable. This xdaforums page suggests CIDManager is causing the phone to reboot upon SIM insertion no matter what. Using ABD App Control, I was able to search “CID” and the “Configuration update” app showed up as a result. Going to Apps > Sort (Enable “Show System Apps”) > “Configuration update” and then clearing data, stopping, and disabling this app allowed me to prevent the phone from updating.
Here were the steps:
- Take out SIM card.
- Download SamFW Tool – change CSC to GSC. Phone reboots.
- Disable Configuration update app.
- Insert SIM and go to APN settings to customize.
I had a similar issue with the Samsung A53 where I could not enter custom APN details. Changing the CSC in SamFw Tool allowed me to switch to GSC. However, inserting a SIM does not cause a mandatory reset and cause me to revert the CSC. Editing the APN settings are working with GSC set as the CSC.
Hope that helps someone!