Tata Teleservices Limited (TTSL) is reportedly in talks with international mobile roaming service provider Matrix Cellular to buy a majority stake in the latter. According to the proposed deal, TTSL will initially acquire a 15 per cent stake in Matrix, which will be gradually increased to 75 per cent. Matrix is valued at over Rs 3.5 billion with a targeted growth rate of 35-40 per cent expected in fiscal year 2009. The Mobile Store, the telecom retail arm of the Essar Group, is also believed to be in talks with Matrix for a proposed merger.