[asterisk-users] How to setup redundant SIP peers

[Thomas Balsfulland]

Hello list,

I try to setup an asterisk-server with different SIP-Peers to PSTN.
The Peer are working and configured in sip.conf:

  [peer1]
  type=peer
  host=10.10.10.1

  [peer2]
  type=peer
  host=10.10.10.2

Now dialout is no problem. Extensions.conf says:

  exten => _0Z.,1,Dial(SIP/49${EXTEN:1}@peer1,30)

But how can I setup a failure-route if the SIP-Proxy "peer1" ist not
answering (in 3sec) or send "50x" error? 
Next idea is to use both peers in round-robin, if they are working.

Could someone help?

Regards
  Thomas