Display a list of items

Hello, similar to, I also would like to display a list, but a list of phone number … where can I STORE that list.
For the moment I have created a “text” helper which contains the last called phone number … but it is rested each time a new call is made. I would like to make “LIST” of all the phone numbers, then display them.

Here is my test helper

and here is my automation writing the phone number in that helper … but how do I ADD a new phone number every time, on top of already existing phone numbers in that helper ??