I. Introduction
Today's service providers are receiving a growing number of data from various communication channels that they are interacting with their subscribers who are may evaluate their products and services. The data can arrive from different communication channels including social media, customer call center calls, emails, forums and blogs, customer reviews, surveys and chat [1]. This data, on the other hand, is a significant asset for gaining competitive advantages for service providers. It is mostly not easy to extract relevant information from this mostly unstructured data.