[Asterisk-Users] help understanding sip header - OPTIONS

[Olle E. Johansson]

These OPTIONs packets are what we send for qualification, a scheme that 
can also be used for NAT keepalives. You turn them on by adding 
"qualify=yes" in the [peer] section of sip.conf

With qualification on, we regurlarly measure the latency between
Asterisk and the client and decide whether the client is reachable or not.

Sometimes these generate odd answers, like 404 Not Found. Do not worry, 
it doesn't mean anything. It's not very beautiful but it happens.

/Olle