Patton electronics 2720/I Series User Manual page 10

Substitution (B8ZS): This mode assures proper bit density
in the data stream. In this mode any data pattern can be
transmitted without causing ones density errors. This mode
allows for 64 kbps clear channel timeslots.
Position
S2-1
S2-2
S2-3
S2-4
S2-5
S2-6
S2-7
S2-8
Switch S2-5: DS0 Channel Rate
Use Switch S2-5 to set the DS0 rate.
SW2-5
Off
On
S2 SUMMARY TABLE
Function
Data Rate
Data Rate
Data Rate
Framing & Coding
DS0 Rate
Clock Mode
Clock Mode
Reserved
Setting
56 kbps
64 kbps
Factory Default
On
On
On
Off
On
Off
Off
Off
9
Selected Option
1.536 Mbps
(DTE Rate)
ESF/B8ZS
64 kbps
Network
Network
Reserved