Yes, Ting will work on generator power. In fact, for homes with a built-in backup generator, Ting will notify you should you lose power and generator power comes on. Note, however, that your internet modem/router and Ting Sensor should be on a circuit that the generator will power in case of a utility power outage.
Utility Power Outage. With a utility power outage, your generator will switch on. There is typically a slight delay between the loss of utility power and the startup of the generator. Your Ting Sensor may temporarily lose power or connectivity during this brief delay, and your Ting Sensor app will notify you of such.
Generator Power On. Subsequently, once the generator has started and is feeding power to your home electrical system, Ting will notify you that generator power is in use. How so? Utility and generator power are essentially 'the same' but vary regarding subtle characteristics such as frequency and harmonic distortion. Ting is designed for discerning slight variations in these power characteristics and can identify when generator power is fed into the home.
Utility Power Restoration. When utility power is restored, and your backup generator is no longer feeding your home, Ting will generate notifications that utility power has been restored and generator power is no longer on.
Test Mode. Note that most home generators, when running in "test" mode, don't transfer power to the home, so in this situation, you will not receive a notice from Ting that generator power is 'on.'