3-prong outlets have been the norm for decades; however, some older homes don't yet have them, or if they do, they are in short supply.
If your home does not have any 3-prong outlets, or if the only 3-prong outlets are in the kitchen, an adapter can be used.
First, PLEASE don't break off the grounding prong on your Ting sensor (or from any plug or device). This would be a safety issue, void the sensor's lifetime warranty, and prevent Ting from properly operating.
Ting can be plugged into a 2-prong outlet using an adapter readily available online or at a local hardware store.
IMPORTANT: 2-3 prong adapters come with a small metal grounding clip attached to them. The clip is a square-shaped piece of metal with a circle in the middle. This grounding clip helps secure the adapter to the outlet. Install the outlet cover plate screw through the hole in the metal ground clip.