Hardware

MSG2

KX-TAW84891 2-Channel Message Card

EXT-CID

KX-TAW84868 Extension Caller ID Card

ECHO8

KX-TAW84866 8-Channel Echo Canceller Card

DPH4

KX-TAW84861 4-Port Doorphone Card

LCOT4

KX-TAW84880 4-Port Analog Trunk Card (2)

CID4

KX-TAW84893 4-Port Caller ID Card (LCOT4 Daughterboard, not shown)

HLC4

KX-TAW84870 4-Port Hybrid Extension Card (1+1 integrated)

PLC8

KX-TAW84876 8-Port Proprietary Extension Card (2)

RS-232 interface never worked on my unit. Nothing visually suspect. I considered replacing the MC1488/MC1489 line drivers, but they're not that easy to get in the surface mount packages. There's also a TI LV11A (triple 3-input AND) on the serial lines (under the board) that is another suspect.