As Kakao Talk (hereafter KT) has been updated lately, adding friends who have phone numbers with different country code from you have become quite confusing.
Now, you can also add friends through ID search or QR code.
I doubt I would ever scan QR code to add KT friends but.. I guess someone else could use this way..
You can still add KT friends by adding their phone numbers to your contacts.
It just got a little bit more specific and that is quite reasonable.
You registered KT with a certain number and this number never goes away.
This number could be your phone number, number given from Messaging Apps or etc.,
anyways you will be able to locate it in "My Profile" and there is a country code your number is from.
If I want to add friends from the same country, you can simply add their phone numbers in the contacts and they'll be added automatically or manually every time you want to sync.
The problem is when you have friends abroad using different country codes.
Forget about how it used to be.
From now on add or edit the numbers like this:
+82 10 1234 5678
(when you are not in S. Korea and you want to add someone who is in S. Korea)
(do not forget to add + and omit the first 0 in area code for Korean numbers)
+1 778 123 4567
(this is when you are not from the North America and you want to add someone who is in the North America)
(again, do not forget + is followed by country code and area code and then phone number)
Again, the formula is
+country code area code phone number
and omit any 0 between country code and area code for Korean numbers.