Tata Consultancy Services (TCS) is set to secure a $2 billion deal from Bharat Sanchar Nigam (BSNL) to roll out its 4G and 5G services across the country. However, the final approvals from the publicly-owned telco may take a couple of months, sources in the know said. As part of the deal, TCS will develop 4G core and Radio Access Network (RAN) technology for BSNL's telecom services.