Did you ever find a fix for this issue? I am running in to the same problem. Agents answer the phone and there is no one there. The caller also hears dead air yet the call stays connected on the agent's phone.
If there is Burst rings configured on the lines from the PBX or from the PSTN then this will result in the phantom call as the gateway does not identify this as a keepalive or burst rings but it treats it as a control signal for another call.
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.