Yes, of course you can! Activate any Add-Ons (Data/ Streaming/ Social/ Voice) of your choice on the app when you purchase your monthly plan, or whenever you need it. Want to know how to activate your Add-On to your plan? Click here.
Add-Ons are not a replacement for your plan. It will expire once your current plan expires except 7days/30days Streaming, Social and Roaming Add-Ons.