Using S50 Yeastar and once a customer calls the PABX, the call gets answered first. After that the call will wait for 10 seconds and start a busy tone. Only then my PABX starts to ring. Can i make the PABX also ring the same time when am getting a dial tone on my phone? Or atleast change the busy tone to some custome music or tone. Here is the link to the video i made explaining the problem.