Hello,
For standalone endpoint for making SIP call you need not to configure anything
For H.323 call you need to configure CallSetup Mode: "Direct" under H323 config.
Also, you need to configure some public DNS server so that it can resolve the queries.
In both cases you need to open proper ports on firewall for communication below are the required ports-
For SIP -5060-TCP
RAS) - Port 1719 - UDP
H225 call Setup - Port 1720 - TCP
H.245 - Port Range 5555-5574 – TCP (in case of dynamic you need to open 11000 to 20999 )
Video - Port Range 2326-2485 - UDP
Audio - Port Range 2326-2485 - UDP
Data/FECC - Port Range - 2326-2485 - UDP
Thanks
Please rate if it is helpful...