These days with caller id on land lines and mobiles if the crew member conciders himself/herself too important to be called on a d/o they do not have to answer the phone.
I personally do not have a problem with being called on a d/o, I have been on both sides. When trying to sort out a disrupted flying programme, you tend to know which crew members will help out.
I now enjoy the d/o payment at the end of the month
