Patton electronics 2720/I Series User Manual page 20

This enables information to be sent over a T1 connection
without any constraints on the data's pulse density. This is the
most acceptable way to accomplish 64 kb/s on each DS0
channel.
B7ZS: This stands for Bipolar Seven Zero Substitution. Instead of
introducing bipolar violations, this method substitutes a one
for a zero in bit 7 (out of 8) of a DS0 channel when the data in
that channel are all zeros. This is a special form of AMI and is
compatible only with special equipment. For most applica-
tions, AMI or B8ZS will suffice.
DS0 Line Rate: 64kbps (default)
Options: 64kbps, 56kbps
64kbps: Also known as Clear Channel, this takes full advantage
of the available bandwidth in a DS0 channel. Implementing it
usually requires B8ZS line coding. In certain cases, special
equipment may implement Clear Channel using AMI or B7ZS.
Consult the equipment manual for compatibility. Your carrier
will advise you on whether to use 64 or 56 kb/s. Campus
applications may not have such restrictions, enabling you to
use 64kbps. In Unframed format, the 24 DS0s and the fram-
ing bits are combined to provide 1.544Mb/s for your use.
56kbps: This uses only the first seven bits of the DS0, limiting the
data rate per DS0 channel to 56 kb/s. Your carrier will advise
you on whether to use 64 or 56 kb/s. This is not available
when using the Unframed format.
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