BSNL is providing free missed call alert service for its customers while the same is charged by the private operators. It comes handy when the mobile user is out of coverage area or battery charging is exhausted. It may be useful to check who all had called us when our mobile phone is switched off or when we are out of coverage area.To activate this free missed call alert service, just go to call settings option in your mobile phone settings menu and select call divert option. Under this you have several options like whether to divert all calls or only when out of reach or when you are busy attending some other call. Select any option and then select activate and enter the number 17010. After activation you can check whether it is active or not by selecting check status option as well as you can deactivate this service at any time.