Tata group telecom companies TTSL and Tata Teleservices (Maharashtra) Limited (TTML) have threatened to pull out of the apex Advisory Council for Telecom (ACT) in India due to issues regarding verification of subscriber base and selling of pre-activated SIM cards. It has asked ACT to "rethink" on the issues, failing which it would surrender its membership. TTSL and TTML favour 100 per cent verification of the subscriber base for national security reasons and have also sought a curb on sale of preactivated SIM cards.