Not if your firewall is well-configured.Does having the 3CX server installed on LightSail give any issues with the 3CX mobile apps?
Have you enable Echo Cancellation in the app? Also, what codecs are you using? What phone is that too?Lots of echo and back ground noise.
Both on LTE and WiFi.
Founded in 2005, when VoIP was an emerging technology, 3CX has gone on to establish itself as a global leader in business communications.