The only reason I am able to mobile mine is because of the app I was talking about in this video. I download the android app and it is called Minergate, however you must go to the website and register, it is called minergate.com
the app is developed so that it uses your phones cpu power for hash rate. hash rate is the rate one is able to solve blocks on the block chain. However, your phone is not the only cpu power that is doing this. Your are actually part of a cloud mining pool on minergate along with other miners using their own cpu power. There are various cryptocurrencies on minergate.com that are offered to be mined.

There is another option when it comes to mining. Instead of using your own equipment, you can pay for hash rate. In this case when you pay for hash rate you are actually "leasing" the equipment to do mining. You don't ever see the equipment because this equipment is probably in a warehouse somewhere in iceland in what you call a mining farm where are people are paying for "leasing" mining equipment aka hashing power. This is very popular way to earn cryptocurrency.

In regards to efficiency in mining with your phone, I feel that it is with Bytecoin. With the other coins, it will take too long to make 1 unit of it. Its not enough power.