Idea Cellular, now an Aditya Birla Group company, will invest Rs 7.5 billion in Uttar Pradesh (East), Rajasthan and Himachal Pradesh in the next three months. Besides aiming for an initial public offer (IPO), the cellular service provider is also planning to enter the Mumbai market as the seventh operator. Further, it is aiming to increase its subscriber base in Maharashtra to 3.5 million this year at an investment of Rs 4.5 million. The company has also applied to DoT for a national long distance (NLD) licence along with Tata Teleservices and Spice Telecom.