Login to the system shell as a root user and execute command that would match the port for traffic you would like to capture:
Full SIP traffic
tcpdump port 5060 -s 0 -w debug.pcap
SIP traffic for specific IP address
tcpdump -i any port 5060 and host 192.168.1.59 -s 0 -w debug.pcap
SIP + RTP traffic for specific IP address
tcpdump -i any host 192.168.1.59 -T rtp -vvvvv -s 0 -w test.pcap
NOTE: Please make sure to replace IP address so it matches the address you want to perform debugging for (most often that will be your provider IP).
tcpdump -i any port 25 -s 0 -w debug.pcap -vv
Download the file from PBXware by either using GUI utilities that support connection on port 2020 or using SCP from your Linux terminal:
scp -P 2020 email@example.com:/path/to-the/file /destination/folder/on/your/hdd/
Download 'Wireshark' program from 'https://www.wireshark.org/'
Once Wireshark is installed open your pcap file with 'Wireshark' and analyze the content.
If you don't have the knowledge to analyze the captured traffic Bicom Systems Support team will be glad to do it for you.