The whole point of POW is to secure the network with lots of hash calculations (hence the term 'work'). Phones have very little power (compared to asics, or even desktop cpu/gpu), so is it impossible for coins mined through phones to have any value and have a secure network at the same time.
And if you are saying like that and then you didn't even see how ETN works this day. i have tried it and i able to mine coin use phone but it's not worth to do that consider about that will be only burning our phone.
You can take a look at ETN and Picoin.