The Full Form of TTSL is Tata Teleservices Limited.

Tata Teleservices Limited (TTSL) is an Indian broadband and telecommunications service provider based in Mumbai, Maharashtra, India. It is a subsidiary of the Tata Group, an Indian conglomerate company. It operated fixedline services under the brand name Tata Tele Broadband in various telecom circles of India. On August 2017, Tata Teleservices sought to exit mobile network division due to heavy losses and debt and sell its unit to Bharti Airtel in a debt free and cash-free deal and described as virtually free and Airtel will only pay a part of Tata Teleservices’s unpaid spectrum payment liability. In November 2017, Tata Teleservices customers transitioned to the Airtel mobile network under an Intra Circle Roaming (ICR) arrangement. SIM cards and billing plans remained the same.  The consumer mobile businesses of Tata Docomo, Tata Teleservices (TTSL) and Tata Teleservices Maharashtra Limited (TTML) have been merged into Bharti Airtel from 1 July 2019