After reading lot of blogs and websites, I could conclude the only below listed use cases for Big Data for telecom market.
1. Customer churn prevention
2. Customer loyalty
3. New Campaign Management
4. Call Detail Record Analysis
5. Network Performance and Optimization by reading logs from the various devices
6. Fraud and Suspicious traffic detection
7. Contact Center Text Mining
8. Multi device event stream analysis co-relating Firewall & IDS & Switch activity
Feel free to comment if you have more.