The OneSimCard Assist app makes it easier for international travelers to make a mobile phone call while roaming internationally. The dialer of the app will automatically correct a misdialed number. The app will add international prefixes and country codes. It will also drop or add zeros where needed or prompt the user to enter a correct phone number without sending a misdialed call to the carrier for connection.

These features will reduce both erroneous call billing due to misdialed numbers and aggravation during international roaming. The app also works with any SIM card, not only with OneSimCard.