Pure scam. No such grants program exists. Do a web search on Federal Government Grants Scams for lots of info on this and similar versions of the scam. Remember, you have to apply for a government grant and there is no upfront fee to receive it.
This particular scam uses their own spoofed numbers to "verify" their original call - turn & turn about - probably if you call any 2 of the numbers, you'll end up talking to the same person!