Cisco IP Phone 8851 Manual

The Cisco IP Phone 8851 is a high-quality, full-featured VoIP desk phone designed for business environments. It features a high-resolution color display, support for up to 10 lines, integrated Gigabit Ethernet switch, Power over Ethernet (PoE) support, HD voice, and a wide range of enterprise telephony features. Below are key sections for safety, features, installation, setup, operation, and troubleshooting.

Features at a Glance

Key components: High-resolution color display, Handset with HD voice, Keypad, Line/Feature buttons, Speakerphone, Navigation cluster, Headset port.

Installation

Unpack and inspect contents. Place on stable desk surface.

1. Connect to network: Use Ethernet cable to connect the LAN port to your network switch.
2. Connect PC (optional): Use second Ethernet cable from PC port to your computer.
3. Power the phone: Use PoE from switch or connect the optional power adapter.
4. Connect handset: Plug the handset cable into the dedicated port.
5. Connect headset (optional): Plug into the headset port on the back.

WARNING! Use only approved power sources. Ensure network cables are properly seated.

First-Time Setup

Phone will boot and attempt to obtain network configuration automatically.

1. Initial boot: Wait for phone to complete startup sequence and display main screen.
2. Check registration: Verify the phone has registered with your call control system (CUCM, CME, etc.).
3. Configure settings: Press Settings button to access network, sound, display preferences.
4. Set up voicemail: Follow prompts or contact administrator to configure voicemail.
5. Test call: Make a test call to verify audio quality and functionality.

CAUTION! Do not unplug during firmware upgrade. Contact administrator for specific configuration.

Specifications

• Model: Cisco IP Phone 8851.
• Display: 5-inch color LCD, 480 x 272 pixels.
• Network: Dual 10/100/1000BASE-T Ethernet ports with integrated switch.
• Power: IEEE 802.3af PoE (Class 2) or 48 VDC external power adapter.
• Audio Codecs: G.711, G.722, G.729a, iLBC, Opus.
• Protocols: SIP (Session Initiation Protocol) and SCCP (Skinny Client Control Protocol).
• Dimensions: 8.5 x 10.9 x 6.1 inches (216 x 277 x 155 mm).
• Weight: 3.75 lbs (1.7 kg).
• Operating Temp: 32°F to 104°F (0°C to 40°C).
• Compliance: FCC Part 15, UL/CSA, CE, RCM.

Controls and Settings

Access menus via the touch screen or physical buttons.

Front Panel: Handset, Display, Soft keys, Navigation cluster (Up/Down/Left/Right, Select), Volume rocker, Mute button, Headset button, Speakerphone button, Keypad.

Settings Menu: Network configuration (IP address, VLAN), Sound (ringer, handset, speakerphone volume), Display (contrast, backlight timeout), Phone configuration (line appearance, speed dials), Security settings.

Administration: Most advanced settings are configured via the call control system (CUCM) web interface by your administrator.

Connecting to Network

Ensure proper network infrastructure is in place.

1. Turn off phone and network equipment before connecting cables.
2. Connect LAN cable from network switch to the phone's LAN port.
3. Connect PC cable from phone's PC port to your computer (optional).
4. Power on switch, then phone. Verify link lights on Ethernet ports.
5. Phone should obtain IP address via DHCP. Check status in Settings > Network.

Tip: For PoE, ensure your switch provides sufficient power (Class 2). Use Cat5e or better cables.

Basic Call Operations

Making and receiving calls.

1. Make a call: Lift handset or press Speakerphone. Dial number using keypad. Press Dial soft key or #.
2. Answer a call: Lift handset, press Speakerphone, or press Answer soft key.
3. End a call: Hang up handset, press Speakerphone button, or press EndCall soft key.
4. Hold/Resume: Press Hold button. Press Resume to return to call.
5. Mute: Press Mute button to toggle microphone on/off.
6. Adjust volume: Use Volume rocker during a call for handset/speaker volume, or when idle for ringer volume.
7. Transfer call: Press Transfer, dial target number, press Transfer again to complete.

WARNING! Emergency calls (e.g., 911) may have special routing. Confirm with administrator.

Advanced Features

Conference: During a call, press Conference, dial second party, press Conference again to merge. Voicemail: Press Messages button or voicemail speed dial. Follow prompts. Call Forward: Press CFwdAll soft key, dial destination number. Speed Dials: Program via Settings > Phone > Speed Dials. Headset Mode: Press Headset button to toggle headset use. Bluetooth (optional): Pair compatible headset via Settings > Bluetooth.

Care & Cleaning

Unplug power and network cables before cleaning. Use a soft, dry, lint-free cloth. For stubborn marks, slightly dampen cloth with water only. Do not use liquids, aerosols, or abrasives directly on the phone.

CAUTION! Do not allow moisture into openings. Keep away from extreme heat and direct sunlight.

Regulatory Information

FCC Part 15: Class A digital device. Complies with Canadian ICES-003. This device complies with Part 15 of the FCC Rules. Operation is subject to the condition that this device does not cause harmful interference. Copyright © 2025 Cisco Systems, Inc. All rights reserved. Cisco and the Cisco logo are trademarks of Cisco Systems, Inc. For technical support, visit www.cisco.com/support or contact your network administrator.

Troubleshooting

Reset: For factory reset, press and hold # while plugging in power. Release after second ring tone. (WARNING: Erases all local settings).

Service: Contact Cisco Technical Support or your authorized reseller. www.cisco.com/support