TNG receives the call details from the PABX. The Mitel has a SMDR port that we connect to access the call details. TNG will display what it receives from the PABX.
With the VoIP solution, the Mitel can be configured to connect to the VoIP direct or it can be routed via a gateway or device. If the service provider pulls billing reports from their own devices(that can detect connect and disconnect of conversations - like Telkom), it will differ from what TNG is receiving from the PABX.
The call details is provided by the PABX unit and this is what TNG works with.
Suggestion:
TNG has a feature to discard calls of a configured duration - see forum post: TNG Costing of calls.
NOTE:
- For analog lines the ring time will be part of the call duration. The PABX will give the call duration from the time you pick up the phone and start dialing until you put the phone down(it does not have the actual connect and disconnect of conversation events).
With digital lines you will not have this problem. - You will have partially dialed numbers that shows a call made.