Introduction

This service description document details the Inband Signaling (IS) protocol between Transcoder/Rate Adapter Units (TRAUs) for speech traffic channels for the Tandem Free Operation (TFO) of speech codecs, sometimes also termed “Vocoder Bypass”. It is applied to the cdma2000 standards.

Annex A is mandatory and defines the capability and requirements used in the development of this TFO standard.

Annex B is mandatory and describes the general IS protocol, which is applicable to TFO specifications for all systems (e.g., TDMA, cdma2000, GSM and UMTS)

Annex C is informative and gives the rules for In Path Equipment (IPE). It is identical for all systems (e.g., TDMA, cdma2000, GSM and UMTS).