In Califonia cause of the ST Andreys fault line where the PACIFIC PLATE and the NORTH AMERICAN PLATE slide pass each other.
Thus, my ballpark estimated cost (basically for the AT&T conference call, $50 witness fee, $150 process server's fee; $400 deposition transcript, $25 for copying costs, and about 10 hours of legal work amount to a grand estimated total of about $625 plus 10 hours of legal work.
The USPTO also charges fees to maintain issued registrations, including $100 per class for filing evidence of continued use (referred to as a Section 8 Affidavit), $200 per class for filing a declaration of incontestability (referred to as a Section 15 Affidavit) and $400 per class for an application for renewal.