We are sent to Palo Alto on business visas which are (as per USCIS) strictly for business meetings and not for working from there. When we are sent there for months and work on projects, we have had issues with immigration the next time around and visas got rejected for other people of the company's India subsidiary because of this misuse.
Now, before someone from HR responds to this, please check records of Indian employees travelling to US from 2012-2106 and check what visa was applied for.