Embed Notice

@cwebber Also on how it could have ended up in implementation:
https://en.wikipedia.org/wiki/X.25

VC may be established using X.121 addresses. The X.121 address consists of a three-digit data country code (DCC) plus a network digit, together forming the four-digit data network identification code (DNIC), followed by the national terminal number (NTN) of at most ten digits.