[asterisk-users] DID failover

[Todd- Asterisk]

I'm setting up an asterisk server where an administrator will not  
always be available in case of problems.  While I expect problems to  
be rare, I need to be prepared.  We're thinking of VoIP DID's and SIP  
phones so it's an all TCP/IP network.   We could get a second server  
to substitute - What is involved in 'transferring' or 're- 
registering' the DID incoming lines to a second server in case the  
primary is down? If there a better fall-over method?  I'm looking for  
the easiest way for the un-educated sys-admin-apprentice to handle  
it.   The system doesn't exist yet so any suggestions are  
appreciated.   I recognize I'll need to modify the SIP phones- I'll  
figure that out later.
  thanks in advance
      Todd