Furious customers disputing bills, issues of payments between operators for roaming services, sim clones and illegal eavesdropping, troubleshooting in multi-vendor - These are some of the most well-known issues faced by Telecom Operator. What if there was a way to overcome these issues. The potential benefits would be huge and at same time greatly improve perception of Operator in eyes of its customers. One such disruptive technology, Blockchains, which uses Distributed Ledgers and operates trustless, is being envisioned to solve such problems within Telcos. A lot of literature is available describing how blockchain can be used to power todays Telecom use cases, however, hardly any papers describe the challenges that needs to be overcome to actually make blockchain a mainstream technology in Telecom sector. This lack of reality check was inspiration for writing this paper. In this paper, we try to understand Blockchains, some proposed blockchain implementation for Telecom use cases and challenges that need to be addressed to enable these use cases.