Just don't pick up. I had the same calls from 4 different numbers starting with the same 923 beginning numbers. Apparently these calls are originating from Pakistan, area code +92.

I have no idea why would somebody be calling me from there over the past 2 weeks. I don't know anybody travelling through there!

These are the numbers that have called me:
+92-34-6579-4092
+92-34-1795-5649
+92-33-6753-9950
+92-34-1799-0793

Got a call from 923-225-247756. Did not anwser the first couple of calls. By the third call I anwsered the phone and could not make out the langange they were speaking. They have called me 6 more times but I haven't answered my phone.