How to make all SIP traffic use an outbound proxy?

[kohenkatz]

I need to have all my outbound traffic go through a proxy (Kamailio) so that internal IPv6 servers can communicate with external IPv4 and so I can do media transcoding (RTPEngine).

As far as I can tell. there is no direct support in dialog.Dialog (or dialog.Transport) for setting an outbound proxy.

I was thinking that it looks like there are two ways I can implement this:

1. Reimplement Dialog to change the send method.
2. Prepend msg.Route of all outgoing messages with a Route header that points to the outbound proxy.
3. Use only the data structures in the sip package and do all the communication work and session tracking myself.

The obvious benefit of the second option is that it allows me to take advantage of the full benefits of this package, but are there any downsides to it? Will it actually work? If not, what is the best alternative to avoid reimplementing most of the dialog package?

Has anyone else done this who can share their experiences?