This Recommendation specifies the formats and codes of the Bearer Independent Call Control (BICC) protocol for the support of narrow-band ISDN services independent of the bearer technology and signalling message transport technology used. It also specifies ISDN user part messages and parameters required to support basic bearer services and supplementary services according to ITU-T 4.761. Where a message, a parameter, a parameter field or a parameter field value is not supported by one of the two protocols or they interpret a code point differently, it is indicated in this Recommendation.