RFC 3966: The tel URI for Telephone Numbers

https://www.rfc-editor.org/rfc/rfc3966.html

[ E.123 ] International Telecommunications Union, "Notation for national and international telephone numbers, e-mail addresses and web addresses", Recommendation E.123, February 2

Having a bank account without having a phone number

https://www.devever.net/~hl/phonebank

and overpriced telecommunications networks ever to have blighted the earth, at least in this century), the carrier eventually decided I clearly don't need the number after all and

Asterisk™: The Definitive Guide

http://www.asteriskdocs.org/en/3rd_Edition/asterisk-book-html/asterisk-book.html

Tailor-made private telecommunications networks Low barrier to entry Hosted solutions of similar complexity to corporate websites Proper integration of communications technologies

Find more...