Google Voice is using this number as CID for GV calls routed to IPKALL virtual/voip phone numbers in the 206/253/360/425 area codes. The reason for this is to get around IPKALL's call termination fees.

If you are a GV user pointing to an IPKALL number, you will see this instead of your GV number. If you call other people who use IPKALL, they will see that number as well. I do not know if *all* called numbers in those area codes will see that or not.

This could be the beginning of the end for totally free phone calling to/from our PC, since IPKALL makes its money from termination fees. If GV gets around paying them, IPK can't afford to keep giving out free numbers.
Cranky Bear
 Jul 12th, 2011
This is the number that Google Voice uses to pass calls on to Washington state phone numbers. So the calls could be from anyone using Google voice.
 Jun 13th, 2010
We got two calls at 3:30 and 4:00am, with no one on the other end. Return call gave a busy signal.
 Nov 26th, 2009