Cisco DP-9851-K9 9851 IP Desk Phone 6-Line Gigabit PoE VoIP PhoneOS SIP CUCM Webex Carbon Black - New

The Cisco Desk Phone 9851 (DP-9851-K9) is an enterprise VoIP desk phone designed for office, home office, and hybrid work environments. It runs Cisco PhoneOS — a single firmware image configurable for Cisco Unified Communications Manager (CUCM), Webex Calling, BroadWorks, and third-party Open SIP platforms. The 9851 features a 3.7-inch color LCD display, 6 programmable line keys, dual Gigabit Ethernet ports, USB-A and USB-C connectivity, Cisco HD Voice with background noise removal on the sending side, and built-in security including TPM 2.0, TLS 1.3, and SRTP.

Cisco 9851 DP-9851-K9 – Key Features & Benefits

• Single Firmware for Multiple Platforms (Cisco PhoneOS): One device configurable for Cisco CUCM, Webex Calling, BroadWorks, and Open SIP / 3PCC cloud platforms.
• 3.7-Inch Color LCD Display (480×240): Backlit screen shows call status, contacts, and menu navigation.
• 6 Programmable Line Keys with Tri-Color LEDs: Six physical line/feature keys with tri-color status indicators. Supports up to 46 total programmable keys when one Cisco DP-9800-KEM Key Expansion Module is connected (sold separately).
• Cisco HD Voice with Background Noise Removal: Cisco HD Voice with AEC, AGC, and VAD. Includes conventional and AI-based background noise removal on the sending side.
• Dual Gigabit Ethernet (10/100/1000) — LAN & PC Passthrough: Integrated 2-port Gigabit switch with one LAN port and one PC passthrough port, both via RJ-45.
• USB-A & USB-C Ports: USB-A port (side) supports USB headsets or the Cisco DP-9800-KEM module. USB-C port (rear) supports USB-C headsets.
• Security — TPM 2.0, TLS 1.3, SRTP, Secure Boot: Trusted Platform Module (TPM) 2.0, TLS 1.3 signaling, SRTP media encryption, Secure Boot, and Image Authentication are standard on every unit.
• PoE Powered — IEEE 802.3 Class 3: Powers via Power over Ethernet from a PoE-capable switch. Cisco Power Adapter 3 available separately for non-PoE installations.
• Hearing Aid Compatible (HAC) Handset: Handset meets T-coil (telecoil) compatibility requirements.
• ENERGY STAR Certified, 74% Post-Consumer Recycled Plastic: ENERGY STAR certified and constructed with 74% post-consumer recycled (PCR) plastic.

Cisco 9851 DP-9851-K9 – Technical Specifications

• Part Number: DP-9851-K9 (DP-9851-K9= is the Cisco spare/resale designation — same device)
• Product Series: Cisco Desk Phone 9800 Series
• Color: Carbon Black
• Display: 3.7-inch color LCD, 480×240 resolution, backlit
• Physical Line Keys: 6 programmable line/feature keys with tri-color LEDs
• Total Programmable Keys: Up to 46 with one Cisco DP-9800-KEM connected (sold separately; 40 keys on KEM + 6 on phone)
• Maximum SIP Lines: Up to 16 (platform-dependent; applies to Webex Calling and Open SIP configurations)
• Softkeys: 4 interactive softkeys
• Fixed Feature Keys: Action, Calendar, Favorite, Hold/Resume, Transfer, Conference, Application, Directory, Volume, Speakerphone, Headset, Mute
• Navigation: 4-way navigation cluster with select key
• Network Ports: 2× Gigabit Ethernet (10/100/1000) RJ-45 — LAN port and PC passthrough
• USB-A Port: Side-mounted; supports USB headsets or Cisco DP-9800-KEM
• USB-C Port: Rear-mounted; supports USB-C headsets
• Headset Jack: RJ-9 analog headset port
• Power: IEEE 802.3 PoE Class 3; optional Cisco Power Adapter 3 sold separately
• Audio: Cisco HD Voice; conventional and AI-based background noise removal (sending side); AEC, AGC, VAD, CNG, PLC; bass-enhancing acoustic enclosure; full-duplex speakerphone
• Audio Codecs: OPUS, G.722, G.722.2, iSAC, G.711 (a-law/µ-law), G.729a/b, iLBC
• Handset: Wideband-capable; Hearing Aid Compatible (HAC / T-coil); RJ-9 connection
• Platform Support: Cisco UCM 12.5+, Webex Calling, Webex Dedicated Instance, BroadWorks, Open SIP / 3PCC
• Protocols: SIP, SDP, RTCP, RTP, SRTP, TLS 1.3
• Security: TPM 2.0, Secure Boot, Image Authentication, SRTP, TLS 1.3, EAP-FAST, EAP-TLS
• KEM Expansion: Supports 1× Cisco DP-9800-KEM; KEM is powered by the host phone via the USB-A port
• Sustainability: ENERGY STAR certified; 74% post-consumer recycled plastic
• In the Box: Cisco 9851 phone, handset with coiled cord, adjustable stand, Ethernet cable (power adapter NOT included)

Cisco 9851 DP-9851-K9 – Frequently Asked Questions (FAQ)

• What call platforms does the Cisco 9851 work with?
  The 9851 runs Cisco PhoneOS and supports Cisco Unified Communications Manager (CUCM 12.5 or higher), Webex Calling, Webex Dedicated Instance, BroadWorks, and third-party Open SIP / 3PCC cloud platforms. Note: native support is not available on all CUCM versions — a device package may be required. Verify compatibility with your CUCM version before purchasing.
• Does a power adapter come in the box?
  No. The 9851 requires either a PoE-capable network switch (IEEE 802.3 Class 3) or the Cisco Power Adapter 3 (sold separately) to operate. The box includes the phone, handset with coiled cord, adjustable stand, and Ethernet cable only.
• What is the difference between DP-9851-K9 and DP-9851-K9=?
  These are the same physical device. Cisco uses the "=" suffix for the spare/resale part number (DP-9851-K9=); DP-9851-K9 is the standard orderable PID. Hardware, firmware, and features are identical.
• Can I expand the number of line keys?
  Yes. One Cisco DP-9800-KEM Key Expansion Module (sold separately) adds 40 programmable keys, for a total of 46. The KEM connects via the USB-A port and is powered by the host phone.
• Does this phone have Bluetooth or Wi-Fi?
  No. The DP-9851-K9 does not include Bluetooth or Wi-Fi. It connects to the network via the wired Gigabit Ethernet port. Headsets can connect via the USB-A port (USB headset) or the RJ-9 analog headset jack.

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