A mobile phone has access to porn, music, movies, animations and games all are haram.
First question is, is it halal to sell such a device? as you are not selling porn itself. I am assuming yes, as anything may have potential to be haram. However this is where it becomes a problem for me, what if your designing the mobile. Or media player (ipod mp4), you have the absolute power to block porn access and music access and games with animations access. But you know if you do this it will be a unsuccessful phone. However you are not promoting these harams, but just designing the phone without actively blocking these for popularity and success and leave it to the customers choice. I will never promote people listening to music, but I understand if I block something like that the phone will be virtually a weak and unpopular device where as if you leave the freedom of it.
The Muslim who fears Allah and the one who is neglectful can decide what they want to do.