Hello I have a location with 3CX and Bero Fix (a gateway for GSM with 2 GSM SIMS) Calls within interiors work ok. Call to any outside number works ok. Call from outside to inside works ok. But, if two interiors, or one external number with one interior, talk to each other and one transfers the call to an external number, the call is connected but only one way audio. Anyone has a similar setup, maybe the same problem and was able to fix it? later edit: Was able to fix it by setting up the option "PBX Delivers Audio" in the gateway settings.