I went travelling for one month and took out my sim card so i would not get any extra charges. I'm on prepaid, and when I returned to Canada it recognized my sim card no problem- but will not make calls! worst part is that I cannot log in to my self serve account because it no longer recognizes my email. If it has run out of money, I can't tell or check, and I cannot call for help because it will not make calls or texts! my phone is a xiaomi Mii that I'm fairly sure operates like an android.