Telecom Regulatory Authority Of India - Subsection
Section 5(2)(c) in The Telecom Consumers Protection and Redressal of Grievances Regulations, 2007
(c)where lesser time limit has been specified by any other law for the time being in force or other regulations made under the Act or by the licensor or by the service provider for redressal of grievance, the Call Centres shall redress the grievances of the consumer within such specified time.