CONTENTS

 1     Scope
 2     References
 3     Terms and definitions
 4     Abbreviations and acronyms
 5     Characteristics of ALC devices
        5.1     General
        5.2     ALC characteristics
        5.3     Tandemed operation
        5.4     Delay performance
 6     Test signals
        6.1     Test signal for level and gain checks
        6.2     Electrical circuit noise
        6.3     Environmental noise
 7     Tests
        7.1     Stability
                  7.1.1     Networks without pre-existing echo control
                  7.1.2     Networks with echo control
        7.2     Echo
        7.3     Noise tolerance
        7.4     Signalling tones
                  7.4.1     DTMF tests
        7.5     Voiceband data and facsimile transmission
                  7.5.1     Disabler characteristics
                  7.5.2     Tests to confirm satisfactory voiceband data and fax performance when an ALC device is not disabled by 2100 Hz
Annex A – Guidance for measuring signal levels in networks
Appendix I – Guidance for the design of Automatic Level Control (ALC) algorithms and their placement in the PSTN
        I.1     Introduction
        I.2     Discussion
        I.3     ALC considerations
                  I.3.1     Location of ALC
                  I.3.2     Algorithmic and subjective considerations
                  I.3.3     Equipment issues
                  I.3.4     Echo
                  I.3.5     Loop stability
Appendix II – Considerations relating to ALC deployment
       II.1     Location of ALC
       II.2     Tandemed operation