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