ESI 50 Communications Server Phone System Upgraded Voicemail (Refurbished)Key Features: ESI 50 includes a built in 482 port card and IVC hardware, along with one expansion slot for another 482 card Simply activate the IVC to add IP phones and or Esi Link licenses ESI Communications Server features: Base Cabinet 4x8x2 60 Hour 6 Port voicemail (5000 0494) Both digital and IP based Standard based design (including SIP support) ESIs Verbal User Guide Six level, 100 branch automated attendant Automatic call distribution (ACD)