A "voice CAPTCHA" is a viable solution. But it does require infrastructure commitments on your part, even if, as you say, an Asterisk box can handle many concurrent calls. If you want to recycle that across multiple customers, that kind of moat can get mildly complicated. The only concern I would have is from a user experience point of view; your customer might not want their callers to have to go through a confusing menu, and it would doubtless be psychologically off-putting. I don't know what kind of business the customer is, but imagine if you called your dentist's office and were prompted to enter some sort of PIN. As a layperson, you might think something is wrong with the phone system. -- Alex Balashov | Principal | Evariste Systems LLC Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free) Web: http://www.evaristesys.com/, http://www.csrpswitch.com/