For this solution I am going to assume
that the buffer uses a baudrate of 4800.
Open your PABX interface. Set your baudrate
to 9600 (default): Options => Communications
Now open your VT100 screen:
1. Set the buffer's end to 4800 by typing:
/P01 4800 now click enter
2. Set the terminal port's end to 4800
by typing:
/P11 4800
Close the VT100 screen and change the baudrate
on the communicatons tab from 9600 to 4800.
Now see whether the data is coming through
correctly on the VT100 screen without the
buffer. And then test it again with the
buffer.