Let customer decide if traffic should be sent to SA

Is it somehow possible to let a peering customer with three adresses, decide dynamically which addresses shoud be open for incoming traffic?

 

The addresses are defined as session-agent's, grouped in session-group and are all "pinged" by OPTIONS.

Normally we would sent traffic to all of them, but if the customer decides to momentarily use one of them for outgoing traffic only, how could that be done? If he stops responding to OPTIONS, the SA will go OOS, but as soon as he sends an INVITE from the SA, it will go In-service again and the SBC will starts sending traffic towards the SA.