The cellphone icon in facebook chat?

[♥~Pretty.Different.*.]

I see the cell phone icon on facebook chat beside some of my friends and sometimes it has some number then m so like 39m or 2m beside it.

I was wondering what they mean because I thought I knew but now I'm not sure. 39m means they were on fb 39m ago but just the cell icon means they are on the app right now, is that correct? Because my friend told me she had to leave but for an hour it still has the cell icon with no 'm' beside it. Can the cell icon also mean that their phone is online and connected to wifi? Or does it mean they are literally still on fb and talking to someone?

[Jeffrey]

It just means that they are using facebook on there phone. And was last seen online checking messages 39minutes ago

[M]

Just the phone icon means that they have Facebook connected to their phone. If there's a time by it, then they WERE online/active that long ago but aren't currently online.