Getting responses behind a firewall / load balancer

[rofr]

Hi friends,

I'm making SIP requests to UDP endpoints from multiple servers behind a load balancer. The endpoints that I am calling will send responses with udp back to the remote endpoint from which it received the original request. This will however be either a NAT gateway or the public IP of the specific instance I am sending from. This mostly works but is not optimal as instances can become unavailable before the response is received. Is there a way to set the public ip/dns name with my request so that the responses go via the load balancer? Guessing this could be as simple as assigning the LocalSIPEndPoint.

[rofr]

Also worth noting is that the load balancer (ALB on AWS) has a name and no fixed IP so it would be good to get the name into the request so that the responding service can do the DNS lookup. The SIPRequest.LocalSIPEndPoint seems to only have IP Address. Perhaps ReplyTo header is the way to go?