iPhone 6s call drop

Hello

This iPhone 6s was dropped. Everything works, charging, touch, fingerprint, display, joins network. 4g also works. But when to make/receive call ... loses network. While using 4G ... 4G text in top bar blinks.

Please guide.. how should I proceed to fix.

Thanks!

crwdns2934089:0crwdne2934089:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2889612:0crwdne2889612:0 0
crwdns2934285:0crwdne2934285:0