bill silva management unhelpfully does not list their phone number or address on their web site, instead offering this lame excuse:

What are the Bill Silva Presents phone and fax numbers? What are the Bill Silva Presents mailing and physical addresses?
As far as the phone/fax numbers and our mailing or phisical addresses, we do not give out that information to the general public for privacy and security reasons. This policy is no different than a private citizen who chooses to have an “unlisted” phone number and address.

One of Bill’s clients, Raul Midon, is much more helpful, offering up the digits:

Bill Silva Management
8981 Sunset Blvd. #303
Los Angeles, CA 90069
phone 310/246-5292

The whois record for billsilvapresents.com turns up the same address with a slightly different phone number (310-246-5210). Likewise for billsilva.net (310-246-5220).

Update 2007-10: Aya from Bill Silva Presents writes that there new number is 310-651-3310.