[Spce-user] correct NAT configuration

[Joan Cifre (ibred)]

Hello all,
we are experiencing many issues regarding to NAT with our SIP 
registration. Our phones register correctly, but if public IP changes, 
the phones failed to register again. We have noted it after a problem 
with DHCP that changed may of the public IPs of our customers routers.
I'm sure it can be optimized and probably our configuration of phones 
and routers is not optimal. The first we can observe is that in the 
Sipwise administration interface, in the registration of the phone, we 
are getting "NAT: no" in all registrations.

User Agent: Grandstream HT701 1.0.0.18
Contact sip:n971520810 at 141.105.96.102:5060
NAT no
Expires2012-12-22 03:52:39

But in fact phones are behind NAT (they have private IP address). Our 
routers have NAT helpers with SIP ports configured (5060, 5061). And 
also our phones have NAT mapping enable set to yes, but no STUN server 
configured. Is there a better configuration than this one? Maybe Sipwise 
could handle the NAT itself? As I told the problem is when the public IP 
changes.

Thanks and regards,
Joan