Tata Teleservices has earmarked an additional $1 billion (approx Rs 4,600 crore) for its GSM service Tata DoCoMo to ramp up its network in the telecom circles where it has already launched GSM services.

The proposed investment is likely to be spent over the period of next two years. The company had already committed an investment of $2 billion (approx Rs 9,200 crore) for the GSM services.

However, the need for the additional investment has come up due to the exceptional growth the company was seeing in terms of customer additions in the telecom circles.

Of the 23 telecom circles in India, Tata DoCoMo was allotted spectrum to launch its services in 18 telecom circles. As of now, the company has rolled out GSM services in 11 circles, namely Tamil Nadu, Kerala, Orissa, Karnataka, Andhra Pradesh, Madhya Pradesh, Haryana, Chhattisgarh, Kolkata, Mumbai and the rest of Maharashtra.

The company is planning to roll out GSM services in the rest of the circles by December 2009.