The language digit defined under §1.1.5 above indicates the service language to be used between operators in the international service,that is to say, the language to be spoken in the incoming international exchange by the incoming, delay and assistance operators when they come on the circuit.The language digit (or information) must be sent on all semi-automatic calls.
ITU-T Q.104-1988 Referenced Document
ITU-T Q.102 Facilities Provided in International Automatic Working - General Recommendations on Telephone Switching and Signalling - Functions and Information Flows for Services in the ISDN - Supplements (Study Group XI) 1 pp*， 1989-01-01 Update
ITU-T Q.107 Standard sending sequence of forward address information