Hi @oej !
Disagree about "I would not expect DNS round robin to work with failover. Just load balancing.", according to doc: ``` use_dns_failover = on |off - if on and sending a request fails (due to not being allowed from an onsend_route, send failure, blocklisted destination or, when using tm, invite timeout), and the destination resolves to multiple ip addresses and/or multiple SRV records, the send will be re-tried using the next ip/record. In tm's case a new branch will be created for each new send attempt. ``` And if we comment out the strings which modify Via hiader in the scenario above: ``` // $fs = "udp:IPADDR_THISNODE:5060"; // This have the same effect as forcing socket // via_add_srvid(1); ``` We have the following signaling exchange: 
If uncomment any of the statement which modify Via then error appear as described in the first post .