[Serusers] AS 5350 + Ser Problem

Hi all, I have a Cisco AS 5350 and two SER.On my CISCO I have an incoming pots dial-peer from PSTN (let's say that it matches 333XXX numbers).Then I have two outgoing voip dial-peers (both dial-peers match 333XXX numbers and are the outgoing routes for these numbers).One of these two outgoing dial-peers is set with a higher preference than the other in order to be the first choice for sending the calls.One of the dial-peers has session target one of the SER and the other has the other SER as session target.So, the main idea is that I want to do fallback between these two dial-peers: if the connection with the first SER (that is with higher preference) is down or there are network problems I want my CISCO to choose the other route to my second SER (and I want it to do that after a specified time).The question is how cand I do that ? And how can I set this timer ?(let's say 10 seconds -> after 10 seconds to choose the other route).What commands do I have to set on the dial-peers and what commands need to be set in the global configuration (timers,etc...)? Thank you very much and I appreciate any help.