Who called from 2155315817

Keep getting a fax machine or some type of auto-dialer calling all the day long every 5 or so mins. I blocked the number so that it stops calling

I have been getting calls all day long from this number and when you pick it up all you get are fax-like squeals. I also tried to call it back and got what sound like a fax machine. Caller ID reads The MCS Group which is in Phildelphia.