How to customize freely Contacts phone numbers format?

I have within Contacts ( the application ) contacts ( the common name ) from a few different countries.

When I enter a new phone number as I want to see and use it,

it is always changed by Contacts, in a way which I don't like

and which I don't use in any other kind of file ( Pages, PDF… ).

I always have to change the phone numbers coming from Contacts. And the worse is

I am getting used to these technical tics which are exactly the opposite of an intelligent use of

an operating system.

For example, for US phone numbers I use the format:

+c xxx nnn nnn

for european phone numbers I I use the format:

+cc x nnnn nnnn

How may I configure Contacts such as it will keep my phone numbers formatted as I write them

at first?

Within the ~/Library/Preferences/com.apple.AddressBook.plist

I found an array structure:

which looks like what has been working for me without problem for more than 10 years ( perhaps more ). During this happy period, the name of this application was Address Book ( if my memory is trustable ).

How may I use these formatting specifications within Contacts?

How may I customize the phone numbers so as to keep them in my personnal prefered format?

If this basic formatting function isn't accessible through Contacts,

which application would you suggest me to switch to to get more freedom

in data presentation preferences?

Thanks to any one who took the time to read up there and try to understand my point.