Need Assistance: Accidentally Disabled Calling on My Mum’s Phone

Hello, fellow tech enthusiasts! I find myself in a bit of a predicament and could really use your expertise. While experimenting with my mum’s phone—curiosity got the better of me—I inadvertently altered a crucial setting. What was once a perfectly functioning device is now a source of stress for both me and my mum.

Initially, I was trying to explore some features and, in the process, typed the code ##4636## into the phone app. However, this accidentally switched her network setting from the standard 2G/3G/4G (LTE/GSM/CDMA auto with PRL) to a restrictive 4G (LTE only). Unfortunately, this change meant that she could no longer make calls, which was not my intention at all.

In an attempt to rectify the issue, I reverted the setting back to 4G/3G (LTE/GSM with PRL). Unfortunately, every time she restarts the phone due to it freezing (the screen tends to go black while at maximum brightness), it defaults back to 4G (LTE only), which disables her calling capabilities.

I’m reaching out for guidance: is there a known way to fix this issue? Additionally, I’m curious if there’s a method to lock the phone into 4G permanently while still enabling calling.

Thank you all for your help! I appreciate any advice you can offer. I must admit, I never imagined my first significant achievement on Reddit would be a plea for assistance in such a predicament!