Does this happen everywhere or in one particular place @Bigbros
This could be network mast congestion or mast issues. Your network will be able to help.
As a process of elimination can you try your sim card in another phone and then see what happens ?
Current Phone ~Samsung Note 20 Ultra 5G SM-N9860_256Gb SnapDragon 865+ Samsung One Ui 3.1/ Android 11.