Options:Following, I am trying essentially the same thing - but I DO have access to the firewall.
I want to register a SIP phone (Linphone or similar) on an iPhone to my PBX, behind NAT firewall.
Since the iPhone will always have a dynamic IP - I am struggling to see how to do that.
For remote extensions, I setup an openVPN on the remote phone itself (Yealink T-48S) with an Untangle firewall.
- Forward all SIP to the PBX, and use Ward's "wide open internet" rules.
- Forward SIP from the carrier's network like @dicko mentioned (but that potentially fails if the phone is on wifi).
- Forward all SIP to the PBX, load a dynamic dns client on the phone and use Ward's Travelin' Man to whitelist the dns name.
- Load a VPN client on the phone.