Social Media Marketing

Such as apps.. ? I know Twitter has that mobile device thing where you put your phone number and receive updates. But I want a way to easily access onto Twitter on my phone. Are there only certain types of phones that can do that?

Ok heres the thing. I have a vu.But i want an iphone to send pictures to twitter on until my aunt told me that u cant send pictures to twitter on an iphone without paying for an internet plan or whatever. Is that true?