When You go abroad, using cellular line is, usually, a problem. Due to expensive international call rates! Fortunately, in recent years eSim become more popular and much more cheaper, compared to regular phone plans. With eSim, you can buy much cheaper plans and use it (usually) more than one country at affordable rates. Great! But there is a problem: When you are in abroad, naturally, you want to use your primary call number by using eSim data line. Here, I will explain, how to use your eSim line to make phone calls with your primary phone number.
Prerequisites
Step-0.1 – I’ll explain the steps according to iPhone, but Android steps must be similar
Step-0.2 – I’m assuming that you have bought an eSim line and installed it properly. If it is not, make it first! I’m using BNESIM eSim and I’m fairly happy. I have used it in many Europe country and worked fine. If you don’t have an eSim plan, you may try it. In addition, you can use M4FZNCXD code, to get 5€ discount in your first fill!
Step-0.3 – I’ll name my Primary phone line as “Primary” and eSim line as “Secondary“
How to Use Primary Phone Number With eSim
Step-1: Open Settings –> Cellular
Step-2: Select Primary at SIMs area.

Step-3: Select Network Selection and disable Automatic (if it is not). Now select your Cellular Line Operator manually. This step is extremely important and must be done before going abroad.

Step-4: Back to previous menu then, enable Wi-Fi Calling and disable Data Roaming. Wi-Fi calling is a good property, you can use it in normal life. By that option, you can call/text even if you are not reachable by Telco operator but Wi-Fi is available, for example when you are in basements. Disabling Data Roaming (at your Primary line) ensures that you will not be charged at abroad.

Step-5: Back to previous menu and select Secondary (new eSim line). At that menu enable Data Roaming (if it is not).

Step-6: Back to previous menu and select Cellular Data to Secondary (eSim line) and select Default Voice Line to Primary (your native phone operator)

Step-7: TEST: Before going abroad, you can test this configuration. Only thing you should is changing your operator to other than yours at Step: 3.
After testing, don’t forget to change it back to your original operator.
Pro Tip: I have changed my operator at Step:3 and tested it without problem. BUT, just before going abroad, made an another test and this time it did not worked! Changed many thing, restarted my iPhone etc. but no way! At the and, I have updated my iPhone’s IOS version to latest one (17.2 to 17.6.1) and worked without any problem! If you meet a problem, you can try it also.
Written by Metin Karal
Metin Karal is a Computer Engineer and He is interested in reviewing products that He used or liked. He also likes programming in C#. Currently, He is developing a really challenging memory game, PairMem which is available at Official Microsoft Store for free download.