Incoming phone call from an unknown number. I am busy coding, the number is not in my contacts, and there is no caller ID. Callers could leave a message on my voice box, but most don't. Callers could send me an email or a short message, but most don't. When I google their number, there is either no entry at all, or one of those generic reverse phone book sites called something like "look who's calling" telling me that it's a German number of an unknown ower. I don't get it.
If making outbound cold calls is your profession, why won't you use any of those free trust-building options? Are those people getting paid just for typing numbers into their keyboard and listening to the ring tone?