On the ATA 186, the first line uses port 1720 and the 2nd line uses port 1721 for signaling when the gatekeeper is present. Ports 1719 and 1739 are used for RAS signalling.
Media ports are from 4000 - 4007 UDP.
They also use the port range 6300 and higher for their TCP SYN packets and H.245 negotiation, whilst the IOS platforms use port range 11000 and higher.
