User Manual for Cisco IP Phone 8851

The Cisco IP Phone 8851 is a high-performance, full-featured VoIP desk phone designed for business environments. It features a high-resolution color display, support for up to 12 lines, Gigabit Ethernet, Power over Ethernet (PoE), HD voice quality, built-in Bluetooth and Wi-Fi capabilities, and integration with Cisco Unified Communications Manager. Below are key sections for safety, features, installation, setup, operation, and troubleshooting.

1. Features at a Glance 2. Installation 3. First-Time Setup 4. Specifications 5. Controls and Settings 6. Connecting Devices 7. Using Phone Features 8. Accessibility Features 9. Care & Cleaning 10. Regulatory Information 11. Troubleshooting

Features at a Glance

Key components: High-resolution color display, Handset, Speakerphone, Navigation cluster, Softkeys, Line keys, Volume rocker, Headset port, Ethernet ports.

Feature	Description
Display	5-inch high-resolution color LCD with backlight
Network	Dual Gigabit Ethernet ports with PoE support
Wireless	Integrated Bluetooth and Wi-Fi (802.11a/b/g/n/ac)
Audio	HD voice wideband audio, built-in speakerphone
Lines/Extensions	Support for up to 12 lines/speed dials
Headset Port	3.5mm headset jack for wired headsets
USB Port	USB 2.0 port for accessories and charging
Security	802.1X authentication, secure boot, encrypted configuration
Power	Power over Ethernet (PoE) or optional power adapter
Protocols	SIP and SCCP support

Installation

Unpack and inspect contents. Place on stable surface.

Connect to network: Use Ethernet cable to connect phone to switch/router PoE port.
Connect handset: Plug handset cord into handset port on back of phone.
Optional headset: Connect wired headset to 3.5mm headset jack.
Power on: Phone will power up via PoE or connect optional power adapter.

WARNING! Use only approved power sources. Ensure network cable is securely connected.

First-Time Setup

Phone will boot and attempt to register with Cisco Unified Communications Manager.

Network configuration: Phone obtains IP address via DHCP by default.
Registration: Phone contacts TFTP server for configuration and firmware.
User configuration: Enter extension and authentication credentials if prompted.
Feature setup: Configure voicemail, speed dials, and other features via web interface.

CAUTION! Do not unplug during firmware upgrade. Ensure proper ventilation.

Specifications

Dimensions: 8.7 x 10.2 x 7.0 inches (221 x 259 x 178 mm).
Weight: 3.3 lbs (1.5 kg).
Display: 5-inch color LCD, 800 x 480 resolution.
Network: Dual 10/100/1000 Mbps Ethernet ports, IEEE 802.3af/at PoE.
Wireless: Wi-Fi 802.11a/b/g/n/ac, Bluetooth 4.1.
Audio Codecs: G.711, G.722, G.729, iLBC, Opus.
Power Consumption: 6.5W maximum (PoE Class 3).
Operating Temperature: 32°F to 104°F (0°C to 40°C).
Compliance: FCC Part 15, UL/CSA, RoHS, WEEE.

Controls and Settings

Access settings via phone menu or web interface. Front Panel: Display, Navigation cluster, Softkeys, Line keys, Speakerphone, Mute, Headset.

Navigation: 5-way navigation cluster for menu navigation. Softkeys: Context-sensitive buttons below display. Volume: Rocker switch for handset, speaker, and headset volume.

Phone Settings: Language, time/date, ringtones, display brightness, network configuration. Call Features: Call forward, call waiting, hold, transfer, conference, park. Audio Settings: Speakerphone gain, microphone sensitivity, audio codec preferences.

Connecting Devices

Network: Ethernet cable to switch. Accessories: Headset, additional handset, USB devices.

Turn off phone before connecting accessories.
Connect headset to 3.5mm jack or pair Bluetooth headset.
Connect USB device to USB port for charging or data.
Connect PC to phone's PC Ethernet port for network pass-through.

Tip: Use quality CAT5e or higher Ethernet cables for best performance.

Using Phone Features

Supports basic and advanced telephony features.

Making calls: Lift handset or press Speakerphone, dial number, press Dial softkey.
Answering calls: Lift handset, press Answer softkey, or press Speakerphone.
Hold: Press Hold button during active call.
Transfer: Press Transfer, dial recipient, press Transfer again.
Conference: Press Conference, dial participant, press Conference again.
Voicemail: Press Messages button or dial voicemail access number.
Speed dial: Press assigned line key or program speed dial via directory.
Call history: Press Directories button to view missed, received, placed calls.

WARNING! Do not expose phone to liquids. Keep away from heat sources.

Accessibility Features

Hearing Aid Compatibility: Meets FCC requirements. Visual Alerts: Flashing LED for incoming calls. Audio Adjustments: Separate volume controls for handset, speaker, ringer. Large Font: Option for larger on-screen text.

Care & Cleaning

Unplug before cleaning. Use slightly damp cloth with mild detergent. Do not use abrasive cleaners.

CAUTION! Do not spray liquids directly on phone. Avoid getting moisture in openings.

Regulatory Information

FCC Part 15: Class A digital device; complies with interference limits for business environments. Copyright © 2025 Cisco Systems, Inc. All rights reserved. For support, visit www.cisco.com/support or contact Cisco Technical Assistance Center. This product contains cryptographic features and is subject to export controls.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Phone not powering on	Power/PoE issue	Check Ethernet cable; verify PoE switch is working; try power adapter.
No network connectivity	Cable/DHCP issue	Check cable connections; verify DHCP server is available; check VLAN configuration.
Cannot register to CUCM	Configuration/TFTP	Verify phone has correct TFTP server; check network connectivity to CUCM.
No audio on calls	Network/audio settings	Check network QoS; verify audio codec configuration; test with different call.
Display issues	Brightness/cable	Adjust display brightness; restart phone; check for loose internal connections.

Reset: Press and hold # key during boot for factory reset (erases all settings).

Service: Contact Cisco TAC: 1-800-553-2447; www.cisco.com/support