They are tough in interviews because they know people will be tough on the phones. They want to see how you respond to rejection and a skeptical attitude. They are going to push you and test your ability to come back from a little attitude. Sell yourself! Don't let their intimidation tactic scare you. They want to see your confidence and your persistence that you want the job and that you will be able to close new business.

She asked basic questions, the phone interview went well so she scheduled me to speak with a hiring manager. You are asked to create a mock sales pitch so be prepared. After this second phone interview I got invited to come into their offices to interview with 3 different sales managers. Overall it is certainly not hard because they want to employ as many sales as possible.