Round-Robion Gateways

I have 3 gateways:

I want incoming calls go t them randomly,something like :
exten => _1.,n,Dial(H323/${EXTEN}@x.x.x.x)
exten => _1.,n,Dial(H323/${EXTEN}@y.y.y.y)
exten => _1.,n,Dial(H323/${EXTEN}@z.z.z.z)

And if one fail try another one (like fail over system).
Is there anyway in Asterisk ?

in SIP i am try this with 3 diffrent peers of 3 diffrent softswtich with diffrent host ip’s
same as you mentioned in H323 ONLY I ADD 20 AT end for time out. onec time out at first gatway it reach to next gateway with next proyority.
in genreal even 1st is congested after that it will come to second one.
i hpe in ur H3223 will be same 7 may work.

good luck

Thanks fro your reply.
Is there any solution which you could limit capacity of each gateways which you send calls to,or calls send to that full ones and after reject send to other gateway?

for that you have to check asterisk conf file like sip.conf
so plz check from