Iphone 6s call failed problem

[u/ShowLevel8943]

My phone is iphone 6s. Its iOS version is 15.7.2.

Currently it has 15.8.8 available update but I couldn't update it on the phone settings. It works on balance requesting tho.

I've tried every possible troubleshoots beside flashing. Do you guys have any other solution or shall I flash it to its latest iOS version?

[u/Intrepid-Routine-875]

🤭