I never answer random calls that haven't been arranged in advance simply because I don't feel comfortable talking to a stranger who could be potentially aggressive, serial timewaster, impolite, rude, rough or even potentially dangerous. I take bookings by text only so that I have time to check CE and think about if I want to see the person or not (it also helps to see who read the profile since I explicitly mention that I take bookings by text, WhatsApp or email only). If the person who sends a message seems ok to me, I then arrange a phone call to hear the voice and to ask a couple of questions and in some rare cases if the guy doesn't sound right to me or ask typical TW questions, after hanging up the phone, I explicitly tell them that for some reasons I don't feel comfortable seeing them.