This program is used for editing your prefix phone number in contact.
Your mobile phone number: 0902145545 and you want to add +84 prefix to your contact to get +84902145545.
Note: If you have a big contact list you need to wait for a few minutes. After completed update you need to recheck your contacts list. In some case, the result is failure but contacts are update successful.
You can install new version of this application which supports more CPU type in https://play.google.com/store/apps/details?id=lhc.app.PrefixNumber