[rscupper]

Most of the boiler room operators use computerized auto dialing.
A computer dials about 6 calls per salesperson, depending on their anticipated hit rate. A salesperson doesn't actually get on your line until they see that someone has answered. About 98% of the time you can tell it's a sales call by the pause after answering. Just hang up.

The computer won't purge your number but it's unlikely you'll get called by that company again for a long time. If you actually talk to them you're likely to get a call back within a week.

Better yet, go for a drive.