asterisk users - Feb 2010 - directmedia/canreinvite/native bridging question

I've got several SIP clients with dynamic IP addresses

Asterisk has one public and one private IP address

SIP clients might connect to Asterisk from either the internet or the
private network (192.168.1.255) - they're portable

By default, directmedia/canreinvite is enabled and Asterisk sets up
direct media connections between clients. In this case clients on the
internet can make calls between each other, and clients on the private
network can make calls between each other, but calls between clients on
the internet and clients on the private network suffer from one way
audio

If I reconfigure Asterisk with directmedia=no then calls between all
clients work, but all audio is relayed through Asterisk - even calls
between clients in proximity to each other on the internet, but far away
from Asterisk : (

I'd like Asterisk to set up direct media connections for calls between
clients who're both on the internet, and for calls between clients
who're both on the private network, but not set up direct media
connections for calls between clients on the internet and clients on the
private network

I haven't yet figured out how to configure Asterisk to achieve this, and
thought I'd ask here if it's possible

I looked at directmedia=nonat, but AFAICT enabling this option won't set
up direct media connections for calls between clients who're both on the
private network?

Does Asterisk support what I describe?

Hi!
> I'd like Asterisk to set up direct media connections for calls between
> clients who're both on the internet, and for calls between clients
> who're both on the private network, but not set up direct media
> connections for calls between clients on the internet and clients on
> the private network 
There is no easy solution available: Consider configuring two 
accounts/two lines per phone, and where possible use the local phone's 
diaplan to select the right one - with or without reinvite. Or next to 
your LAN PBX establish a remote/Internet PBX.

Philipp