No service

Hi, I have a problem with my phone it always shows No service or searching. I have a iPhone SE 2020 (2 gen).I have tried every method whether it is reset network setting or restoring the whole phone and I have even gone to my carrier and asked how to fix this problem they said change the sim I changed but still no service

i have saw that the phone recognises the sim but it shows no network on the about section. Do you guys have any idea how should I fix this problem?