according to my brother, instead of answering 'hello', if you answer 'may I help you' usually stops the calls. (If they get you to answer once they will continue to call)
It is a scam.
The government does not offer grants to individuals for personal use.
It is a scam ran by off shore con artists to trick you into sending unrecoverable money to them.
They will say you need to get prepaid money cards, like Green Dot and load them with you own money or to wire transfer funds via companies like Western Union for fees or tax. Once you give the details from the card to the scammer, they clean out the card. Once you wire transfer money, you can not recover it.
You loose your money, you get nothing.
The only legitimate avenue for government grants is through www.grants.gov which is the official US government web site for grants.
From their FAQ concerning fraud:
http://www.grants.gov/web/grants/support/general-support/grant-fraud.html
Please note the following:
No government grant-making agency will make phone calls; send email or letters to solicit money or personal banking information from a potential grant recipient.
There are no processing fees for federal grants.
Federal grants are not issued for personal use, but are intended for institutions and non-profits to carry out projects with a public purpose.
Know who you're dealing with on the web. Scam artists will often post a website with a name similar to a legitimate site.
If you have provided personal banking information to anyone claiming to be associated with a Federal grant agency, call your bank immediately to prevent unauthorized access to your account.
If you receive a call, mail, email, FAX, or any other form of communication soliciting you for a grant, STOP.
It is a scam.
Report it to the FTC:
http://www.consumer.ftc.gov/articles/0113-government-grant-scams
File a complaint with the FTC. If you think you may have been a victim of a government grant scam, file a complaint with the FTC online https://ftccomplaintassistant.gov/ , or call toll-free, 1-877-FTC-HELP (1-877-382-4357); TTY: 1-866-653-4261. The FTC enters Internet, telemarketing, identity theft, and other fraud-related complaints into Consumer Sentinel, a secure online database available to hundreds of civil and criminal law enforcement agencies in the U.S. and abroad.