This annex contains the description of an algorithm extending ITU-T G.711.1 for the scalable coding of superwideband speech and audio signals from 96 to 112 kbit/s for G.711.1 80 kbit/s core(R2b mode) or from 112 to 128 kbit/s for G.711.1 96 kbit/s core (R3 mode). G.711 superwideband extension codec is interoperable with both G.711.1 and G.711.This Annex is organized as follows. The normative references, abbreviations, acronyms and conventions used throughout this Annex are defined in clauses D.2, D.3 and D.4, respectively. The G.711.1 superwideband extension encoder and decoder functional descriptions are discussed in clauses D.6 and D.7, respectively. Clause D.8 describes the software that defines this coder in 16-32 bits fixed-point arithmetic.