I recently went to Canada, Ting's (corporate) homeland, with two Ting phones, a CDMA iPhone and a GSM android-based phone. I was surprised when we landed in Toronto without any cell service. Calling Ting to troubleshoot, I found Ting has no GSM nor CDMA support in Canada. Lack of GSM support is forgivable, as it's somewhat new, and I didn't call to verify GSM compatibility before leaving the US.
However, I was informed on the phone that Ting is having contract negotiation trouble with their Canadian CDMA partner, and there is no CDMA support either. As a result, we had to resort to burner SIMs for our trip. So, for Ting users traveling internationally, fair warning: Nothing works. And to the Ting folks: This is unacceptable! I recommend you to everyone that will listen, but you need to up your international coverage game.