If you've signed up to OVO Mobile - Mini or OVO Mobile - Small, you have a standard calling allowance and a data allowance to keep track off. When you sign up to OVO Mobile - Medium, Large or Extra Large your calling allowance is for international minutes plus you have your data allowance.
If you're on our kids plans and you run out of your calling allowance you'll need to recharge your whole plan - you can't just top up your calling credit.
If you use up your international calling allowance you've got the option to add OVO Extras or wait until your next recharge. When you recharge you'll be renewing all your calling and data benefits.