Introduction

This service description document details the Inband Signaling Protocol between Transcoder/Rate Adapter Units (TRAU) for speech traffic channels for the Tandem Free Operation (TFO) of Speech Codecs, sometimes also termed "Vocoder Bypass". It is applied to the North American standards TIA/EIA-136 and TIA/EIA-95.

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 Inband Signaling (IS) Principle. It is identical for all systems (e.g., TIA/EIA-136, TIA/EIA-95, GSM) and only updated to include the System Identifications for TIA/EIA-136 and TIA/EIA-95.

Annex C is informative and gives the rules for In Path Equipment (IPE). It is identical for all systems (e.g., TIA/EIA-136, TIA/EIA-95, GSM).