A20 VoIP SIP Telephone, 2 x Fast Ethernet, 2 x line keys, PoE required, AC optional, 2.8 inch colour backlit LCD, HD audio, RJ9 headset jack, EHS support for specific Plantronics headsets (EHS cable SKU #87327-01 required). Optional AC power supply, SKU #1TELD007LF. Note: For use with any Asterisk-based solution, or Asterisk-based distribution, including AsteriskNOW, FreePBX, Wazo, Isaabel, and more. NOT COMPATIBLE WITH DIGIUM SWITCHVOX PRODUCTS. Special Order, No returns or cancellations.