This document holds ANNEX C to the GSMA HD Voice Logo Licence Agreement. Annex C: Minimum Requirements for Mobile Networks and Terminals for the usage of the ‘HD Voice’ logo with GSM/UMTS. This Annex defines the minimum requirements for the usage of the ‘HD Voice’ logo for GSM/UMTS network operators and device vendors. HD Voice (High Definition Voice) for mobile terminals and networks comprises of AMR-WB codec and the enhancements to terminals and networks according to the requirements defined in this document. AMR-WB is the Codec defined in 3GPP TS 26.171. Further information and technical details of AMR-WB are described in GSMA PRD IR36 “Adaptive Multirate Wide Band”.