Facebook help, what does this phone symbol next to people names mean?

[Jack]

So on my friends list on the right, some of them have a picture of a phone with when they were last online for example 42 minutes ago, but some have just a picture of the phone and others have nothing or a green circle thing, i think the green circle means that they are online, but i don't know what the others mean, thanks!

[Ralph Ortiz]

The phone with mins is the mins of how much they have been active before so ya when they were last on and without the mins is their just on mobile but can still recieve msg but are not active on fb and ya the green circle is when their online

[ducky]

The phone Symbol means that they have the Facebook app on their phone. So they can recieve the message whenever as long as they go on the app.

[Super Mario Bros.]

It could mean that they have the Facebook app on their phone, or it could also be a link to send them a text message or call them.