I have extensions in a remote branch office connected via a hardware VPN. The extensions comprise 3cxPhone for Windows and Yealink T22s. I am trying to configure QoS on the router and I need to know the ports used by the extensions to communicate with the 3CX server in head office. What RTP Ports do the 3CXPhone for Windows clients use? There is a pair of settings in the 3CX Server called FIRSTLOCALPORT and LASTLOCALPORT set to 7000 and 7499. Are these the RTP UDP ports? If I look at the web page of the Yealink T22 extensions it says Local RTP Port is in the range 11800 to 11780. Is Local RTP Port what is used to communicate with the server? Or does it use the ports defined at the 3CX server?