I have an iPhone 5 and carrier is Koodo. I purchased the add-on via self serve once in Mexico and have not had service since. Wifi but no telephone or texting. Cannot cancel via self serve and no land line available to call Koodo.
No. Purchasing the add-on will not result in loss of service. Just remember you leave Canada you are no longer on our network but on a number of local carriers'. Quality of coverage may vary from place to place, country to country.