The number is registered in California. Nothing else is available in public records.

Called @ 11:50pm on Monday, May 12th, 2008. Said nothing, but hung on the line for 19 seconds before disconnecting. Returned call @ 11:59pm; got a busy signal.

Tried a second time and got a strange siren sound with the regular "Your call cannot be completed as dialed. Please check the number and dial again." Then a guys voice says "090T".

According to a post on the Binary Revolution Forums "AT&T's internal tandem designations are spoken at the end of the recording. They go from 001T to 145T or so and each one is a different 4ESS. San Bernardino, CA, for example, is 113T, San Francisco is 089T, Oakland is 070T, San Jose is 090T, etc."

So this number is a San Jose number.

Called @ 1:16am on Tuesday, 5/13/08. No message.

I got a call from this number at around 10:10pm PDT on Tuesday May 13th, 2008. The call stopped before I could answer it.  When I tried calling back, I got the same "Your call cannot be completed..." message as Nick.