Description: Indicates the maintenance modes of the Analog voice interface.

                  Managed system
         +=============+=============================+
         |   Voice     |   +===========+   telephony |
   <=====+ application +===+   CODEC   +===end point +=== test
   IP    |   (Host)    | . +===========+ .(Interface)|   equipment
backbone +=============+=============================+
                         .               .
     Host      ======>===+               .
     Compressed   <======+               .
                         .               .
     Host      ===================>======+
     Uncompressed <======================+
                         .               .
     Interface           +========<==========================    
     Compressed          +==================================>
                         .               . 
     Interface           .               +===<===============    
     Uncompressed        .               +==================>
                       Compress      Uncompress 
                       Loopback      Loopback
                       point         point
   
    none(1)  - the interface is not in maintenance mode.
    hostCompressedLoopback(2) - Host Compressed Loopback.
       This mode is set by the managed system to perform the 
       compressed voice loopback test. The voice packet is passed
       by voice application to the interface associated CODEC.
       Instead of feeding these into the CODEC for decompression,
       they are immediately sent back to the voice application as
       if they had originated locally and been compressed.

    hostUncompressedLoopback(3) - Host Uncompressed Loopback.
       This mode is set by the managed system to perform the 
       uncompressed voice loopback test. The voice packet is 
       sent by voice application all the way through the
       interface associated CODEC and then turned around instead
       of being sent to the telephony endpoint.

    ifCompressedLoopback(4) - Interface Compressed Loopback.
       This mode is set by the managed system to perform the 
       interface uncompressed voice loopback test for the 
       external test equipment that is connected to the voice
       interface.
       The voice samples are sent from the test equipment all the
       way through the interface associated CODEC and then turned
       around instead of being sent to voice application.

    ifUncompressedLoopback(5) - Interface Uncompressed Loopback.
       This mode is set by the managed system to perform the 
       interface uncompressed voice loopback test for the
       external test equipment that is connected to the voice
       interface.
       The voice samples are sent from the test equipment to the
       interface associated CODEC. Instead of feeding the voice
       samples into the CODEC for compression, they are 
       immediately sent back to the telephony interface.