Do you have two sim cards in your Samsung J7 mobile? Sometimes you use one sim for calling and one sim for mobile data. So it is very important to select the suitable sim when you are calling or using data. So now you can predefine which sim to use by selecting some options. 

First you need to insert both sim cards to your mobile. Then you need to go to settings.After that you can select connections. There you have sim card manager. Inside the sim card manager you can find sim 1 and sim 2 with the details. Now you can select your preferred sim card for calls, messages and mobile data. 

For example, if you want to use sim 1 only for mobile data first you need to select mobile data. Then select sim 1.
So it is very easy to manage your sims.

Normally when you are in a call and at the same moment if someone tries to call you they will get it as number busy. 
But in this situation you wouldn't know who called you while you are in another call. 

If you are using Samsung j7 you can easily put that second caller as waiting. 
So you can stop or hold the first caller and get the second caller. This facility is really helpful when you are getting so many calls. 
You can take most important calls while you are in another call. 

So when you are in a call if you get another call it will display second callers information. Here you can use hold option to the first caller.
All you need to do is follow these steps.

1.First go to call log.
2.Then click on menu bar.
3.Go to more settings
4.Then turn on call waiting

Do you charge your phone although it has battery more than 60%?It not good for the battery of the phone at all.This unnecessary charging can make your battery life short and it will make battery draining fast.So to charge a smart phone wait until the battery is at-lest 20%. This make the battery life long.Also once a month please restart your phone.That is compulsory.It will make your phone battery life longer.Also when you charge your phone only use the compatible given charger.Don't use any charger that has the port.You need to consider the voltage as well.Other thing is don't use your phone for calling and other stuff while charging.This can explode the phone.

Do you get annoying calls from others?
Now you can easily block these numbers in your Samsung phone.

You just need to go to call settings and then you need to go to block call numbers.
Then you can just type the number and add to the block list.
Then you won't get any unwanted calls from those numbers.
Also you can just go to call settings and then you can check the blocked call list.
And anytime you can unblock numbers as you wish.

Step 1-Go to calls
Step 2-Click on settings
Step 3-Go to block numbers
Step 4-Add the number to block.