VOS3000 billing issues solution – Conversation time is less but charged duration is higher! Why ?

hello, one of the most common things always happened in voip softswitch industry – people had issues with billing disputes with each other – there are many reason for those disputes and 95% time the errors are human errors – software normally not make much issues always – i am now sharing one of the issue here which sometime happen conversation time is lower but charged duration is high !