Call disconnecting
Why is my phone disconnecting the calls so frequently, not able to speak to anybody properly
iPhone XR, iOS 16
See these Apple articles below:
If you see No Service, Searching, or SOS on your iPhone or iPad
If you see No Service, Searching, or SOS on your iPhone or iPad - Apple Support
Manually update your carrier settings on your iPhone or iPad
Manually update your carrier settings on your iPhone or iPad - Apple Support
Update your network provider settings manually on your iPhone or iPad
Update your network provider settings manually on your iPhone or iPad – Apple Support (UK)
If you see a Cellular, Ultra Wideband, or Apple Pay Issue message after an iOS update or restart
If you can't make or receive calls on your iPhone
If you can't make or receive calls on your iPhone - Apple Support
For sure contact your carrier, and check your data plan.