What how come NTC be put inside battery. Usually battery is dc source, any other electronics is placed outside battery. It caanot be placed inside battery.
As Dodgydave has shared most mobile phone batteries not just have a thermistor inside them, but a small PCB too carrying an entire protection and over charge prevention circuit inside them...
If it had only two terminals then in most cases that is just a Li Ion cell, which is similar to any other cell that you are comparing the battery with.