Need help setting up telephony on OLT ZTE C300?

Question

SIP

Good afternoon!
Need help setting up telephony on OLT ZTE C300.
There is a ZTE C300 software ver 1.2.3 with a CTBB streaming board and an ONU ZTE-F660
connected to the GTGO board.
The task is to set up telephony on onushki.
I see everything like this: From the telephone exchange through the E1 stream, we send telephony to the
CTBB board - on the OLT we set up a VOIP SIP server - on the ONU ZTE-F660 we drive in the SIP settings and receive a telephone signal
from the telephone ports of this onushka . The problem is in configuring the CTBB board to receive the E1 stream and VOIP SIP service on the OLT head.

Answer 1

And what does setting voip sip server on OLT mean ?
Haven't seen this, do you have a description?

Answer 2

A CTBB card is inserted into the OLT ZTE ZXA10 C300, which, according to the manual, accepts the E1 stream. The task is to set up telephony at this station, i.e. accepted stream and transfer it to subscriber onu with telephone ports. How to set it all up? Is that the question?