Is this from all your contacts or some of them @United1
Check that none have been blocked in your phone and that the sender hasn't blocked you.
Does this happen everywhere or when your in a certain place like home ?
Check your Network's masts.
Is this both on normal texts or multimedia messages too ?
Check your messaging centre number is correct on the phone.
Try taking the sim card out and give the chip a gentle wipe and reinsert.
If you can as a process of elimination try your sim card in another phone and then see what happens.
Try another sim card in your phone.
Reset your network settings on your phone which may help.
I wish you all the best with this.
Current Phone > Samsung Z Fold³ 5G.