[asterisk-users] SIP tunnel

[Scott L. Lykens]

> My idea is to use a well know port like port 80 (that is not blocked).
Skype for example uses this port.

If you are in a situation where the ISP/government is blocking VoIP you
are probably going to have to encrypt it to get it through, and that may
not even work. I have a client who has facilities in Belize where BTL
apparently employs quite sophisticated deep packet inspection... SIP or
IAX on any port combination would drop about half a second after the
media starts. IPSec over UDP/IKE were completely blocked as well. I
ended up using IPSEC over TCP as it was not interfered with.

If the ISP or government are not the problem, only firewalls... IIRC in
a typical NAT setup you could have the client register to you using IAX
- This will keep the port open through the NAT device so you can send
calls to them without them having to map ports in their firewall.

sl