Telephone Type: Telephone Multiline Operation Capability: YES Lines Supported: 4 Conference Call Capability: Support Voice Mail Capability: Support Speakerphone: Full duplex speakerphone Call Forwarding: Support Call Hold: Support Call Transfer: Support Display Type: LCD Display Volume Control: Support Hearing Aid Compatible: Support Network Ports Qty: 2 Network Protocols: Gigabit Ethernet, SIP Power Over Ethernet (PoE) Support: Support Voice Codecs: G.711 (A-law and U-law), G.729AB, G.722, iLBC, OPUS VoIP Protocols: Support Additional Features: Conversations stay on track. Hear every nuance with industry-leading sound quality featuring Poly HD Voice. Eliminate distracting background noise at the source with exclusive award-winning Poly Acoustic Fence technology. Dimensions & Miscellaneous Color: Black