[Users] how to refresh REGISTER state when restarting redundant proxy

[Juha Heinanen]

Jiri Kuthan writes:

 > I guess that some practical aspects were out of scope of this paper
 > -- it does
 > not seem to seek to provide a full solution.

looks like university guys don't care about real life solutions.  they
just want to get their papers published.  

this reinforces my thought that the only working solution is that UAs
register with all proxies.

until that happens (which may be never), it might make sense to hack nat
helper module to use source ip address from an avp.

-- juha