Hi All, we are trying to move our Level3 SIP trunk from our Fortinet Firewall w/ NAT (too many one way audio issues to count) to the recommended setup of MBG/Proxy - Essentially this should be an easy once since SIP Peer is preexisting and mostly working on VMCD we only spun up MBG Cluster and then select it as Proxy then point Level3 Hunt Group to MBG WAN IPs. Initially this works fine for inbound calls and has been working this way for outbound for some time; however, when we do some inbound call load testing, we eventually start getting random hangups and then see SIP/SIPSm warnings in the VMCD logs - stating "The SIP link Level3-1 has failed with cause: ServerErrResp - response code 503 (Service Unavailable)Far end possibly overloaded or down for maintenance. The link will be retried in 1 seconds." It then comes back up a second later and we can get inbound calls thru. Wireshark on MBG shows the 503 from the VMCD to the MBG stating Reason: SIP;text="Pending SLOWSTART REINVITE conversion";cause=503. Any comments/assistance is appreciated.
