to fonestop, is that "L" TX, Protege had 2 cabinet sizes LTX and Mtx (I think) and a flat pack CTX. LTX had more card slots than MTX. I can't remember vmail part number (SVP8 ??) But, it was interchangeable between MTX and LTX you just couldn't put it in any slot had to be in first 4 or 5 slots because of "time slot sharing" and you need a procomm program that shipped with vmail called "voice"