Please, what do these two icons mean?

Hello, guys.

I've bought a new dual SIM smart phone, a Samsung J2, with Android 5.1.1.

I'm curious about two icons on the top bar.

http://postimg.org/image/9dv62aiy3/

1) What does the first icon (left red arrow) mean?

It is a SIM card icon with number 1 in it. I thought it could be something related to the "Preferred SIM card" option under "SIM card manager", but I've set the "Voice call" option to "Ask always", therefore, IMHO, there's no sense in showing number 1 or 2 on the top bar for that since there's no preferred SIM card chosen. Then, I also thought maybe it could be something to do with the "Text and multimedia messages" option because this one won't allow me to choose "Ask always" like the "Voice call" will. I can choose only one of the SIM cards only. That said, I've chosen SIM card number 1. However, if I choose SIM card number 2, that icon won't change into 2. So, I have no idea what that icon really means.

2) Why is there a kind of a square around the first network icon (right red arrow)? What does that square mean?

In the beginning, I thought it had something to do with "Data usage", as if data usage was on for the first SIM card, but... it is not. My data usage is off for both SIM cards. I'm using my home WiFi, I don't need my data usage turned on.

Well, those are my doubts. I've searched about them on the Internet, but I couldn't really find anything relevant. To be honest, I don't even know if those "icons (as they are)" are Android's or Samsung's stuff. I'm saying that because I haven't seen any Android screenshot with those icons. Maybe it could be some kind of feature Samsung has developed by themselves, I don't know. Anyway, can you help me understad it?

Thanks in advance. I really appreciate your time.

Cheers.

brunces

Edit: Sorry for the external link to the image. I couldn't find a way to embed the image here.

 

scary alien,

Thank you very much for your reply.

Actually, I have this manual and, to be honest, I had already seen what you pointed. Problem is I don't really get it, I confess. I mean, first of all, it doesn't mention -- anywhere -- the meaning of the "box" surrounding the Signal strength. It only shows that both icons (with and without the "box") represent the Signal strength. Maybe your guess is right and the "box" represents the signal strength of the currently in-use SIM, but do you get my point?

Now, the other thing I don't understand... "Currently accessing SIM (Currently in-use SIM)"... What does this mean exactly? Is the phone not using both SIMs at the same time? "In-use" for what? For example, I'm not using my phone right now, I mean, I'm not on the phone with anyone. Both SIMs are activated, enabled to make and receive calls, working properly as usual. Data usage is off for both SIMs (I don't need it, I'm home... WiFi, you know). I'm not even touching my phone, it's just lying on the table and its screen is locked as usual. So what the heck is "currently in-use SIM"? What is SIM 1 being used for that SIM 2 isn't? I mean, aren't both "being used" equally, at the same time, whatever they're used for?

Sorry, those pieces of information from the manual were not clear enough to me. It certainly has an explanation, of course. It's just... I still don't get it, you know? I'm LMAO here.

I hope you understand what I'm trying to say. Anyway, thanks again. I really appreciate it.

Cheers.