[asterisk-users] Server redundancy

[Alejandro Acosta]

Hi all,
  I have read a lot about * server redundancy, however I still don't know
how to do it. Can any of you give me any advise?
  For example, I've read about ranchnetworks appliances but don't know if it
will solve my problems.
  As you may guess, I need to have two servers with the same information
(including configuration, cdrs and logs). Of course, If a server fells down
I would like the IP Phone to register with the other server. 

Can I do that?, do I need a third server?, other appliances?

Alejandro Acosta,