Jed,
You could try the following – instead of A record for each gateway, create single record for SBC1 with the IP addresses of SBC1 and SBC2. On theory, DNS will reply in Round Robin manner and so, every next call would be sent via different gateway. I am not sure thou, if Lync cashes the DNS or makes a DNS query every time sbc1.domain.local is sought.
Drago
http://www.lynclog.com
