Transfer from behind nat to without nat - sip doesn t work

I am working with asterisk since a couple of month working properly - iax and sip - incoming calls and outgoing calls are all fine.
I transfered it from behind nat to a public adress ( without nat) iax is still working fine but SIP doesn t work i can’t receive any incoming calls or make any calls - Can somebody give me some advise concerning sip.conf and sip_nat.conf or maybe some other issues.