Prefixer!

Prefixer allows you to quickly add prefixes and suffixes to numbers in your contacts. It creates new entries for all of your contacts, without deleting any existing information. When youre done travelling, simply disable all the prefixes the app added with one button tap, and maybe enable a different one Because the changes are added as an additional field in your contacts, you can call through with the added prefix or suffix without returning to the app, making for a clean, built-in solution that you can use in the Phone app, Contacts app, or even with Siri