The TMC EPIC ET4000 telephone is made to work with with Centrx lines per the manufacturers instructions. I found a copy of the user guide at
please see page 60 - 63 (70-73 of the pdf file) of this document for the Centrx instructions.
The lines are connected via two separate RJ-14 (2 line version of an RJ-11) jacks and each connection will handle two lines. As Centrex line are analog in nature, I see no reason why this should not work. Each Centrex line will take up one line position within the telephone,
The user guide mentioned above also has specific hook-up information.
Joseph Golan, RCDD