what does just the mobile symbol mean?

[john]

i messaged someone she hasn't seen my message or replied. and she has gone from active "15 hours ago" to just a mobile symbol it has been like this for 2 days now and it has stayed the same. does this happen after being inactive for a certain length of time? or could she have turned me off chat or blocked me? What could it mean?

[Charles]

It means she uses a facebook on phone. You try to use a facebook on phone and it will come the same icon when you go offline. I have seen many icons like that on facebook.
She hasn't blocked you, if someone blocks you, you can't view their profile and they can't view yours. So for example if I block you, I would not be able to view your profile and also you can't view my profile because I blocked you.