Occasionally we see a caller number prefixed with [V] but don't understand what it means or when/why it's added? It doesn't happen every time and we do not have any prefix rules set up.
This is from your sip trunk provider. This means that it passed STIR/SHAKEN validation. It is similar to the caller verified on some newer cell phones.
@Stephen Quam is spot on. This means that your the incoming call has been validated. You can contact your provider to see what they can do but it's not a bad thing to have in my opinion.