[Freeswitch-users] Do I need a STUN-Server?

Hi, I read some docs about STUN/TURN-Servers and I understand the concept behind it (nearly). Do I need a STUN-Server when a SIP-Client (behind NAT) must connect to a Freeswitch-Server (public ip)? Or is a STUN-Server only needed if a SIP/P2P-Connection must be established? Thank in advance, Thorsten