Why do spam callers call and hang up?

Related questions

1. What is difference between WCF and Web service?
2. Will a scammer come to my house?
3. What is the full meaning of WCF?
4. Does WCF support rest?
5. Is WCF a REST or SOAP?
6. Is cold calling illegal?
7. Can I get hacked by answering a phone call?
8. Why do we use WCF?
9. What is WCF soap?
10. What is WCF and why are they calling me?

Tags

1. #phone
2. #cleaner
3. #certain
4. #phones
5. #active
6. #filter
7. #number
8. #calls
9. #valid
10. #wasteful
11. #establish
12. #willing
13. #answer
14. #after
15. #point
16. #spammers
17. #target
18. #robocallers