350 9608G IP phones connected to an IP 500 running BBX, once the calls, which are a combo of SIP and T-1, reach 67-70 concurrent calls, the IP Office starts having awful voice quality and the 500 stops responding to pings. As soon as the calls drop below the 67-70 threshold the system operates normally. Network verified good, and pings to LAN 2 during the outage seem fine.