iPhone SE call-recieving malfunction

Hello fellow fixers

My phone is doing a funny thing when calls come through. I never hear any dial tone, and usually, calls will go straight to answerphone. No issues with volume once the call is answered. No issues with calls from facetime, whatsapp, etc, just normal phone calls.

I changed my battery recently. It might be that I didn’t reconnect something correctly as I put it back together.