Startup Idea : contact number change notifier.

for the past one year i am changing my mobile numbers due to some technical issues and signal issues as i moved from place to place frequently. a i recently visited Indonesia and i found that most of the people change their sim as cost of buying new sim is less than buying internet data, so people buy new sim as they get free internet data. so i would like to create an app which detects the mobile numbers if changed and automatically update all of his friends contacts with his new number instantly.