Currently, formatting a phone number into a human readable format takes quite a bit of work. You have to strip out any non-digit characters, and then split the remaining digits into individual characters and output them one by one. It’s also prone to errors, as you can only support one phone number format this way.
The
e164
filter is useful for getting the phone number into a standard machine-readable format, but it’s not great for user-facing tasks like invoice generation. Implementing something like number_to_phone in Rails would make this kind of user-friendly formatting far easier.