Rajesh Kurup and Surajeet Das Gupta for Rediff

Mumbai/New Delhi, Feb 3: Telecom czar Sunil Mittal has a hectic schedule chock-a-block with meetings every day.

That is why T V Ramachandran, who heads the Cellular Operators' Association of India -- the apex body of GSM technology service providers -- sends him a missed call if he has something urgent to discuss, rather than disturbing him.

Mittal calls back when he is free. It's a code both understand well. Ironically, for Mittal's Bharti Airtel and the other eight major mobile operators in India, missed calls are becoming a growing headache.

Despite call rates being as low as Re 1 or less, ballpark industry figures show that over 30 per cent of all mobile calls are missed calls. They are deliberately made to convey a pre-agreed message or are calls that go unanswered.

A study by Learning Initiatives on Reforms for Network Economies (Lirne), a Denmark-based NGO that focusses on telecom issues, shows that over half of India's 140 million mobile subscribers make missed calls to convey a pre-agreed message.

As many as 95 per cent of the pre-paid customers used missed calls for this purpose, the study added.

For operators, missed calls clog networks without earning them revenue, also frustrating genuine callers with "network busy" messages.

"Missed calls use microwave links, the backhaul and the exchange and yet we make no money," said a senior executive of Hutchison-Essar.