Amazon.com : Axtel AX-400G IP Phone - 8 SIP Accounts, 5-Way Audio Conference Bridge, Dual-Port PoE Gigabit Ethernet, Illuminated 2.8" 320×240 Pixel Color Display, Crystal Clear HD Sound, EHS Capable - Black :
Converter Adapter | Converts RJ-9 to 2.5mm for phones that have a 2.5mm jack., (2200-11095-002) | Use with APP-50, APP-51 EHS for Polycom, Connecting telephone devices to 2.5mm headset mini jack
GRANDSTREAM GXP2140 Enterprise HD Voice IP Telephone, color high reso