[asterisk-users] OpenVPN on phones?

[Dave Platt]

> Anyway - is there someone out there that know the behaviour of OpenVPN in regards of retransmits and such? A VPN that retransmits will at some point hurt you if you transmit media over it, especially if you scale it up.

OpenVPN is well-behaved in that way.  It uses SSL over TCP for its
"administrative" communications between peers - authentication
and key exchange and other protocol negotiations.

The VPN traffic itself - the payload - isn't sent over TCP.
Instead, the incoming packets are tagged, encrypted, and
transmitted via UDP, on the usual best-efforts basis.  OpenVPN
will not, itself, retransmit those payload packets.  It's
up to the endpoint protocols to do so, if they so choose.

I've had quite good luck carrying SIP traffic over OpenVPN...
used it between a hotel in Norway, and my home in California,
a couple of weeks ago,  Even with the hotel end of the
connection being over WiFi, I didn't notice any significant
packet loss problems.