Do I need STUN?

Question

My router has a "real" static outer IP address. Behind router's NAT there is an Asterisk server. Router is configured to forward 5060 UDP port to Asterisk machine. Do I need STUN server assuming that SIP clients will be in other cities, behind their own NATs?

Answer 1

With static public IP address you do need STUN. It wouldn't hurt using it, but you can configure public IP statically:

[general]
externip=63.182.70.1
localnet=192.168.0.0/255.255.255.0

[peer1]
type=peer
nat=yes
qualify=yes

(example from http://www.smartvox.co.uk/astfaq_configbehindnat.htm)

You most likely would also need to forward RTP port range on router. Change port number on which asterisk is listening to other than 5060. One reason is security (less chance of random SIP scan), second - less risk of problems with router ALG.