Ring-beep on internal busy calls

[xptpa2020]

We have a customer that would like internal calls that are busy to have a different ring in the caller's ear than that of the standard - for instance, if I am on my mobile phone and somebody calls me, they do not hear the standard ring, but rather a ring-beep, alerting them to the fact that I am on the phone. Our customer wants a similar experience for his Yealink IP to IP internal calls that ring a busy extension.

It seems that if a mobile phone can do this, an intelligent IP phone should be able to achieve the same, but we cannot seem to find the configuration variable to provide such.

BTW we use asterisk ver 11 and 13