Hello Richard Clark,
Welcome to Apple Support Communities. What is the specific iOS 16 version installed on your iPhone? Settings > General > About.
Are you experiencing this behavior while being connected to Wi-Fi, cellular data, or both?
iOS 16.0.3 was released recently, so if you haven't updated yet, please back up your iPhone, and update. You can find the steps to back up, and update in the following link:
Update your iPhone or iPad - Apple Support
If that didn't help, don't restore your device to factory settings. Please reach out to Apple Support to investigate this issue further. You can contact them using this link:
Apple Support
We hope this information is useful. Kind regards.