Japan’s NTT DoCoMo and Tata Sons have decided to make an open offer to acquire 20 per cent stake in Tata Teleservices (Maharashtra) Limited at Rs 24.70 per share. The offer will open on January 8 and close on January 27, 2009. The move follows NTT DoCoMo’s acquisition of 26 per cent stake in the Tata Group’s unlisted company, TTSL, for $2.7 billion.