Whitepages.com analyzed back in 2014 the 2.5 billion calls and texts routed through its Caller ID app and came up with the top 10 spam area codes in the United States.

1. 313 – Detroit
2. 713 – Houston
3. 954 – Fort Lauderdale
4. 404 – Atlanta
5. 484 – Eastern and Southeastern Pennsylvania
6. 407 – Orlando
7. 214 – Dallas
8. 202 – Washington, D.C.
9. 972 – Dallas
10. 205 – Birmingham

This is obviously in addition to toll-free "area codes" such as 8xx.

Put your hands up for Detroit!