Modern international signalling systems are capable of exchanging signals corresponding to indications normally given to subscribers by means of audible tones (busy, congestion, ringing, etc.). Administrations are encouraged to arrange their networks so that these information signals can be sent between countries in order that they can be recognized and converted into tones or announcements as near to the calling subscriber as practical. This procedure could significantly reduce the language problems arising from the growing use of recorded announcements.
1988ITU-T E.181-1988 Customer Recognition of Foreign Tones - Telephone Network and ISDN - Operation, Numbering, Routing and Mobile Service (Study Group II) 2 pp