In countries where missed calling is common, some wireless carriers have shown concerns that the practice uses their networks in a manner they cannot derive revenue from.[1][6] In August 2005, a Kenyan mobile operator estimated that four million missed calls were placed on their network daily.[7][8] In 2006, industry estimates indicated that 20–25% of mobile calls in India were missed calls.[9] In 2007, the Cellular Operators Association of India announced that it would conduct a study on the effects of missed calls on Indian mobile networks.[9]