There are 5 FIR's (Flight information regions) in  India as shown in the image above . There are also 14 Control areas (TMA) and 2 Indian Air Force Control areas within the FIR's , as mentioned in the ENR 2.1-1 of the Indian AIP LINK where detailed information is available

FIRS

1. CHENNAI - CLASS D AIRSPACE

VOMF_CTR       Chennai Radar        125.700
VOMM_APP     Chennai Approach   127.900
VOMM_TWR     Chennai Tower        118.100
VOMM_GND     Chennai Ground      121.900

2. DELHI  - CLASS D AIRSPACE

VIDF_CTR        Delhi Control          120.900

VIDF_CTR        Delhi Radar             124.550
VIDP_APP       Delhi Approach        127.900
VIDP_TWR       Delhi Tower            118.100
VIDP_GND       Delhi Ground           121.900

3. KOLKATA - CLASS D AIRSPACE

VECF_CTR        Kolkata Radar          127.300
VECC_APP       Kolkata Approach     127.900
VECC_TWR      Kolkata Tower          118.100
VECC_GND       Kolkata Ground        121.900    

4. MUMBAI -  CLASS D AIRSPACE

VABF_CTR       Mumbai Radar         125.900
VABF_CTR       Mumbai Control      132.600
VABB_APP      Mumbai Approach   127.900
VABB_TWR     Mumbai Tower         118.100
VABB_GND      Mumbai Ground       121.900

5. GUWAHATI - CLASS D AIRSPACE

VEGT_CTR       Guwahati Control        123.900
VEGT_APP      Guwahati Approach     120.500
VEGT_TWR      Guwahati Tower          118.750