[Kamailio-Users] Dispatcher

I wish to implement a kind of a failover situation, probably using the dispatcher module. We want to monitor our gateways by performing a range of tests (not just a ping or INFO but also waiting for a specific response to an INVITE). If the test fails then we want to mark a gateway as unavailable until the tests are successful again. Based on a bit of reading I think we could use the dispatcher module in database mode. We could run a script that performs the tests and marks the destination as inactive if the test fails. If that would work, can anyone advise how we mark a destination as inactive? It looks like the MI function ds_set_state does this but can I update the database directly? If so what field do I need to update? Thanks Cameron