[asterisk-users] call across 2 asterisks

[unplug]

How can I make this work (UA1 makes call to UA2)?
If I issue a command Dial(SIP/UA2), the call will fail.  Someone in
the forum said that Asterisk doesn't support the configuration below.
But I am thinking about the possibility to make it works.  Anyone can
share if it really works?

UA1                UA2
------NAT1        ------------NAT2
  |		         |
  |		         |
Asterisk1	Asterisk2
  \		        /
   \	             /
 --------- (ARA) DB----------------