They just benchmark your phone and according your hardware specifications you get a certain reward in a given time - "hash rate". No mining involved in the real meaning. Well, I don't really see the point of getting rewarded for nothing, but this is their strategy. At least you are not killing your battery/phone by doing this so called "mining".
Aren't they pooling the hashes came from phone cpu's? Isn't cryptonight cpu minable? I don't get it.
They call it > The Mobile Mining Experience, see the quite below, source at the bottom.
The Mobile Mining Experience
While mining for Electroneum, your phone wont be performing real mining (as is done with a computer), but rather a simulation of mining.
The Electroneum team has described their mobile app as a Mobile Mining Experience.
Instead of actually using your phones CPU to solve complicated cryptographic problems (as is done with real mining), the app will continually monitor the available CPU power on your phone. In this way, it will determine the amount of CPU power that could have been used for mining, had the phone actually been mining.
Your phone will then be issued with a hash rate (speed of mining, if you will) based on its available CPU power. ETN coins will be credited to your online wallet based on this hash rate.
Link to the source article > https://electroneum101.com/how-to-mine-electroneum-with-a-mobile-phone/