[bitfolk] Port 1720 filtered

Hi All, I ran a port scan on my own server out of curiosity and noticed something quite out of place... Not shown: 996 closed ports PORT STATE SERVICE 22/tcp open ssh 53/tcp open domain 80/tcp open http 1720/tcp filtered H.323/Q.931 22,53 and 80 are the ones which should be open, so what on earth is 1720? I have tried to locate the process behind it..."lsof -Pni :1720" brings nothing back and "netstat -tulpn" is also not bringing anything up, there is also nothing in iptables (I haven't got round to setting it up yet). Is it something in the Bitfolk network? Just want to know what it is really.. Daniel