Hello,
I'm having almost the same issue. After 15:30 minutes into the call the audio disappears. The call is not terminated, but no side hears the other. The logs continue to show that call is active.
I'm using 3CX V9 SP5a on a VOIP provider (Israeli 073 NetVision). I've set:
Supports Re-Invite: true
Supports 'Replace': false
PBX Delivers Audio: false
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