Videocon lost 14.09 lakh customers while Idea's user base declined by 3.87 lakh subscribers in April. The overall subscriber base of these companies fell to 51.54 lakh and 17.46 crore, respectively.
Besides, Telenor lost 25,496 customers in the reported period.
Videocon had already announced a deal to sell its spectrum in six circles to Bharti Airtel.
The GSM subscriber base stood at 77.39 crore at the end of March.
Market leader Bharti Airtel added 9.78 lakh subscribers to take its base to 25.22 crore, with a market share of 32.60 per cent.
Aircel's customer base soared by 5.72 lakh to 8.76 crore and state-run MTNL also added 10,091 subscribers.
COAI did not report the GSM figures of BSNL, Reliance Communications and Tata Teleservices.