i want to connect a tda 620 with another pbx

[roh]

hi all

my english lang is awful so i'm sorry about that

we have a panasonic tda 620

and all of extension is full

so we want add another panasonic pbx and connect to this pbx

can we do this?

i think the name of this work is "TIE",is it?

if we can do this so whith what which model of panasonic we can do and how?