This is a mortgage refinance call.

15 calls from this number in 20 days. How do I stop them???

DNC Complaints:
https://complaints.donotcall.gov/complaint/complaintcheck.aspx

Also file a complaint with your State Attorney General's office.
List of State AG’s offices:  http://800notes.com/faq/attorney-general

Call Blocker
You need to buy a standalone call blocker, call blocking phone, use your carrier’s call blocker if they offer one, or download a free call blocking app for smart phones.  For conventional cell phones, assign the number a letter like “z” and make no ring.  You may also need to have your carrier increase the ring time to avoid having them leave a message on your voice mail.