Difficult to diagnose further without a proper packet capture, screenshots of sngrep are of limited use.
You may have a NAT detection /Traversal issue. Why does the INVITE go to 41@1 something when 41 is actually 41@v something? Are 20,22,21,1,10, and 23 all on the same public IP address? If they are, they can't be all using port 5060 unless they are on the same phone or something like a multi line analogue adapter.
Is this a new installation? Is this a customers router? I ask because not all NATs are the same, some cause real problems. Also are there any SIP ALGs enabled on the router, these also cause problems more often that not.
PM me with a download link if you want to send me a full packet capture.