Syntax for Alternate host in SIP trunk

I have a SIP provider with 2 signaling hosts. How do I add it to the SIP trunk to make sure that when one is down the other will work seamlessly?
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And I want to add another host say 82.XXX.10.12…

You can only have one host per peer (FreePBX configures trunks from peers)

You need to create a second peer (trunk) and put that as the second target of your outbound route.