🚀 go-pugleaf

Vint,

X.121 is for data network addresses (i.e. both X.21 and X.25). In
addition, X.121 defines escape digits 0,8,9 for Telephone, Telex and
Telephone (again) numbers. (Two escape digits for telephone for
administrations who need to handle digtal and analog systems
separately.)

(It is possible that this escape digit business was added to X.121 to
support Teletex, which in some countries uses the Telephone
network for transport, whereas in other countries use the public data
network. It also allowed interworking with Telex. As you can see, it
comes in handy for addressing Fax and Telex from X.400, too.)

+---------------------------+------------------------------------------+
! Peter Varlien             ! X.400: C=no;ADMD=Telemax;                !
! Product Specialist MHS    !        PRMD=Norsk Data;O=ND ServiceTeam; !
! ND ServiceTeam            !        OU=Trondheim S=Varlien;G=Peter    !
! (a division of Norsk Data)! Internet: Peter.Varlien@Trondheim.       !
! N-7004 Trondheim, Norway  !           ND-ServiceTeam.Norsk-Data.     !
! 'phone: +47-7-921222      !           Telemax.no                     !
+---------------------------+------------------------------------------+