No ringback after changed 'DetectOutboundConnectMethod' value

[Thunnderman]

No ringback after changed 'DetectOutboundConnectMethod' value to either 'Detect Speech' or 'Detect Polarity reversal' unless changed it back to 'none' or 'assume connected after a short delay' when making a outgoing call from PSTN?

Is this a bug or intentionally for other purose?

[RonR]

Ringback on PSTN line calls comes from the LINE Port provider.

Detect speech : The call is not bridged unless/until non-ringback/non-silence is detected.

Detect polarity reversal : The call is not bridged unless/until the LINE Port provider reverses the line polarity.