On 19 January 2018, the Telecom Regulatory Authority of India (TRAI) permitted the use of mobile phones and internet access through Wi-Fi on-board all flights operating in Indian airspace. However, passengers are only permitted to make mobile phone calls when the aircraft is at an altitude of over 3,000 metres (9,800 ft). TRAI stated that the height restriction was to ensure "compatibility with terrestrial mobile networks".[40][41]