Functioning as the rear board of the enhanced control plane unit (ECU), the E1/T1 interface board (ETI) is generally used together with matching subboards. The ETI provides various interfaces for the universal process blade (UPB) to communicate
with external devices. ETIs are classified into ETIA0, SSIA0, and SSIA2 by interface function, as described inTable 1.

Table 1 ETI Board

Board	Interface Function
ETIA0	Is a narrowband E1/T1 interface board, configured with two ETMA subboards, and provides 32 E1/T1 interfaces.
SSIA0	Is a channelized interface subboard, configured with two TSCA subboards, and provides two channelized STM-1 interfaces.
SSIA2	Is a channelized interface subboard, configured with one ETMA subboard and one TSCA subboard, and provides 16 E1/T1 interfaces and one channelized STM-1 interface.

documentation very useful for my job

Can you please share the capacity calculation mechanism of UNS board?

Useful for Gb over FR network.....

Yes it is used together with matching sub boards

useful document, thanks