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HUD3 requires TCP port 5222 to be open for connectivity. Please make sure that TCP port 5222 is open on your firewall and/or router and being forwarded to your PBX server so that all HUD3 traffic can reach your Fonality server.
HUD 2 (legacy)
When using HUD from alocation a location remote to the Fonality server, connection settings must be changed. If you are still using HUD2, please watch our instructional video for remote HUD use at How do I configure HUD for remote use?