Recommendation I.252.2 (11/1988): Call offering supplementary services: Call Forwarding Busy (CFB)
superseded recommendation/international standard from the International Telecommunication Union
ITU Telecommunication Standardization Sector
Call offering supplementary services: Call Forwarding Busy (CFB)
Recommendation I.254.1 (11/1988): Multiparty supplementary services: Conference calling (CONF)
Recommendation I.254.2 (11/1988): Multiparty supplementary services: Three-Party Supplementary Service (3PTY)
Recommendation I.256.2a (11/1988): Charging supplementary services: Advice of charge (AOC)