Who called from 2815378409

Got one at noon today, I didn't answer they left no message.  I am assuming this is a tele-marketer?

Got a call yesterday, they did not leave a message.  Also received one from 281-537-7552 and the same thing, no message.

Just received a call from them. I answered and they hung up.

Got a call from this number on Oct. 3 @ 4 p.m.  Missed the call, so I returned the call & no one answered.  I do not know who this would be or why they are calling me.  I don't have any medical bills that needs to be collected...I pay my bills.  Wish this number would be blocked.

I got a call and someone hung up. Whats the point of hanging up if you're some stupid scammer or salesperson. Can our highly paid phone companies investigate this number.