Speakerphone Wireless Headset Compatibility 2.5mm Headset Port 4 Soft Keys 24 Programmable Buttons 242 x 55 Monochrome Backlit LCD 4 SIP Accounts SIP Compatibility - RFC 3261 Standard SIP Server, Asterisk® & BroadSoft® IP Version IPv4 Extensive CODEC support: G.711μ-law, G.711A-law, G722, G.726, G729a HD Voice & Power Over Ethernet (PoE) Support Electronic Hook Switch Control Port AC Powered (Adapter Not Included) Two Ethernet Ports 500 Phone Book Entries