Adding International Code to Numbers?

[northy124]

Is there a way to add international code to the beginning of numbers already entered? I have gone through all the settings and am unable to find an option to change it 🙁

Is there a way or do I have to go through all 300 contacts and manually change them 😡

 

[miles01110]

do I have to go through all 300 contacts and manually change them

Yep.