TLDR; If I store a phone number in MySQL(or any DB with equivalent constraints), would the correct format be E.164 values into a VARCHAR(32) field?
Have been reading up on format/storage of international phone numbers. In the past for various reasons it was suggested to store as a string due to this data being an identifier not an actual number(along with issues like leading 0's). I'm aware that I should not attempt to parse/validate phone numbers via regex, and that libphonenumber developed by Google is generally recommended for handling this and producing E.164 formatted values.
I'm assuming it's safe to say E.164 is the best suited storage format for phone numbers today. As the leading + does not seem required and that leading 0's would not occur in this format? I've seen BIGINT(15) suggested for storing this in MySQL databases. This would require an additional field(string?) to support phone numbers with extension numbers. It's not stated on the Wikipedia article but I've seen many mentions in blog posts that the E.164 format supports extensions by appending ";ext=12345" so would it be more advisable to store into a VARCHAR(32) field? "+19995556789;ext=12345", 32 should be the maximum length with this format, so the length of 32 is appropriate? <+><;ext=>
EDIT: I'm not sure exactly what the extension value should be, according to this it is 11, however the article linked to has been modified since and archived by Apple, there is no clear information on extension length there. Would it be best just to a higher limit such as VARCHAR(50), or go with BIGINT(15) and a additional field for extensions that is nullable?