Just wanted to know on an MGCP SRST setup, what tcp/udp ports do you need to block on a backup WAN link if you want to activate SRST when main link is down. We blocked tcp 2000 on the backup link but its not working. The phones go into fallback mode but we are unable to dial out. Only works when both WAN links are down. Do we need to block mgcp udp port 2427?