With the application running any phone numbers copied to the clipboard will be
converted into +12345678900 format.
Example
I made this script then I was converting all my contacts to this format. Here
was the procedure:
Open a contact
Double click and drag to select the entire number
Press ctrl + v
Go back and open another contact
Known Issues
To save a step, this script uses xsel rather than xclip to read input. For
some reason text seems to only be recognized if selected using a double-click
and drag method.