The number of mobile phone users in the country is all set to increase to 500 million by 2010, Union Minister for Communication and IT Dayanidhi Maran said today.Speaking at a national conference on "Managing Corporate Growth", organised here by Bharathidasan Institute of Management, Tiruchirapalli, Maran said the number of cellular phone customers had already increased from 75 million in 2004 to 175 million till September this year.The central government's policy of encouraging the manufacture of cost-effective mobile phones had encouraged international companies to invest in setting up manufacturing plants for cell phone components in the country, he said.Maran also said the government would encourage Indian entrepreneurs to set up software companies in the country.