Ernest Mavrel wrote:

I need to rewrite the To URI because of my provider. He expected all numbers in e.164 format. Unfortunately some users start calls in international format, some in national. I changed R-URI, but provider also check line "To" in header. So I need to change that line to.

That's strange.  Unless your provider is routing on the To header, which it should not be, it should be of purely cosmetic significance.