What happens next?

How to call an unknown number
Listen for single rings.
Be suspicious if you hear your phone ring once. A single-ring missed call could be the work of a " crammer ": someone who is trying to get you to call them back so they can charge you.

OPTIONS: a. Additionally, if someone calls three times in a row, the operator will want you to ignore the number altogether (not simply ring 4 times). Look to see if the number is about to ring again.; b. If you only hear one ring, don't call the number back. If it wasn't a crammer, it was probably a wrong number.; c. Be especially wary if you hear the same number twice. Instead of interrupting other customers (" hey, chase, hold on ") hear a number while sitting at the table.; d. It's a secure line and should not be monitored. If you hear one-ring, that is a good sign.;
b.