This is very good advise! The most important thing you can do Always, is to answer your phone. Carry your phone with you no matter where you go, including next to the shower when you are in there. Over the years I have actually taken assignments with shampoo in my hair.
For newbies this is crucial. By not answering your phone you may not just be missing out on one assignment but the beginning of a whole relationship with a company trying to hire you for the first time.
This need to answer the phone is demonstrated in a video I made which you might want to look at. The link is: