Mumbai, June 13: The Reliance-Anil Dhirubhai Ambani Group will invest close to Rs 1,600 crore to expand its GSM-based mobile services.

Group firm Reliance Telecom Ltd (RTL), which operates in eight circles, is planning to cover 4,300 towns from the existing 300. The group has a subscriber base of over 21 million users in both CDMA and GSM-based mobile services.

Sources said the company will float a tender of 10-12 million lines within next year as part of the expansion plan.

The circles where RTL has GSM operations include Calcutta, Bengal, the Northeast, Assam, Bihar, Orissa, Madhya Pradesh and Himachal Pradesh.

Recently, Reliance Communications, formerly known as Reliance Communication Ventures, the fully integrated communication business provider, had approached the department of telecommunications (DoT) seeking spectrum to offer GSM services in the lucrative circles of Delhi and Mumbai. The group is a major player in CDMA-based mobile services and hopes to carve a significant presence in the GSM space as well. The DoT is yet to take a decision on Reliance’s application

While RTL offer low call rates in Calcutta, observers said Anil Ambani might chalk out an aggressive plan after the group enters Delhi and Mumbai with its new offering.