They have called 3 days in a row at 8 in the evening no one there. I held on but they just hung up

I get calls from this number almost daily. Never a message and calling back gets "Nanos Research" recording when you call back. Very annoying. Fortunately, they almost always call during the day and my service takes the call. Here's a link to their contact info from their website:  http://www.nanosresearch.com/company/contact.html

I received a call from this number this evening, Friday, March 13 at 7:03 atlantic Daylignt Time. Noone answered when I picked up.

Who is this/  And why won't they leave a message???  I pick up the phone, but then they hang up!! Grr!!!!!

I get calls from this number almost daily. Never a message and calling back gets "Nanos Research" recording when you call back. Very annoying. Fortunately, they almost always call during the day and my service takes the call. Here's a link to their contact info from their website:  
http://www.nanosresearch.com/company/contact.html