[Freeswitch-users] Call quality troubleshooting best practices

Can someone point me to any resources for troubleshooting call quality issues using freeswitch CDR or logs, or whatever tool I may be missing? We are having a hard time time pin pointing where intermentent call quality issues source from, and running a packet capture for long periods of time on our server and the customer firewall seems clunky. I was wondering what the pros are doing when users report issue with call quality. Thanks in advance!!