You can't call 611 if you were travelling outside of Canada. The call barring is likely from the Mexican cellular carrier (not from Koodo).

If you want to check your voicemail, you could dial your own number from your Koodo handset. That would help you to access your voicemail. However, you might have to pay extra roaming fee for doing so as you were in Mexico.

I have international data roaming and international voice roaming on my Koodo phone and I have the mobile data turned off. Will I be able to call my phone or do I need to do something else so I can make the call to Canada?

As of now, can you connect to any local network? if you were connected, then you can make calls.

Also, make sure you know the rate of easyroam while traveling https://www.koodomobile.com/easyroam