Cisco 6851 IP Phone Manual

The Cisco 6851 is a business-class IP phone featuring a high-resolution color display, support for up to 12 line appearances, integrated Gigabit Ethernet switch, Power over Ethernet (PoE) support, HD voice quality, built-in Bluetooth for headset connectivity, and advanced security features. Below are key sections covering features, installation, configuration, operation, and troubleshooting.

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

Features at a Glance

Key components: Color LCD display, Handset, Speakerphone, Navigation cluster, Soft keys, Volume rocker, Headset port, Ethernet ports.

Feature	Description
Display	High-resolution color LCD with backlight
Line Appearances	Supports up to 12 lines/phone numbers
Network	Integrated Gigabit Ethernet switch with PoE support
Audio	HD voice quality, wideband audio support
Bluetooth	Built-in for wireless headset connectivity
Security	802.1X authentication, encrypted signaling
Headset Port	3.5mm jack for wired headset connection
Speakerphone	Full-duplex speakerphone with echo cancellation
Power	PoE (802.3af) or optional power adapter
Firmware	Field-upgradable via TFTP/HTTP/HTTPS

Installation

Unpack and inspect contents. Place phone on stable surface.

Connect to network: Use Ethernet cable from switch to PHONE port.
Connect computer: Use second Ethernet cable from PC port to computer (optional).
Connect handset: Plug coiled handset cord into HANDSET port.
Power connection: Use PoE from switch or connect optional power adapter.
Connect headset: Plug into 3.5mm headset jack (optional).

WARNING! Use only approved power sources. Ensure cables are securely connected.

First-Time Setup

Phone will boot and attempt to obtain network configuration.

Network configuration: Phone obtains IP via DHCP by default.
Phone registration: Enter extension number and credentials if prompted.
Verify registration: Check for dial tone and display showing extension.
Configure preferences: Use Settings menu to adjust ringtone, volume, display.
Test features: Make test call to verify audio quality.

CAUTION! Do not disconnect during firmware upgrade. Ensure stable network connection.

Specifications

Display: 3.5-inch color LCD, 320 x 240 resolution.
Network: 10/100/1000 Mbps Ethernet, 802.3af PoE.
Audio Codecs: G.711, G.722, G.729, iLBC.
Protocols: SIP, SCCP, 802.1X, TLS, SRTP.
Bluetooth: Version 3.0, HSP and HFP profiles.
Physical: 8.3 x 10.2 x 6.5 inches, 2.2 lbs.
Power: 6.5W typical, 12.5W maximum.
Operating Temp: 32°F to 104°F (0°C to 40°C).
Compliance: FCC Part 15, UL, CE, RoHS.

Controls and Settings

Access menu via NAVIGATION cluster or soft keys.

Front Panel: MUTE, HEADSET, SPEAKERPHONE, NAVIGATION cluster, VOLUME rocker, LINE keys.

Display Features: Call status, directory, call history, settings menu.

Settings Menu: Network configuration, Audio settings (ringer, volume, tone), Display settings (contrast, timeout), Bluetooth pairing, Security settings, Phone information.

Administration: Web interface accessible via IP address for advanced configuration.

Connecting Devices

Network: PHONE port to switch, PC port to computer. Audio: Handset, headset, Bluetooth.

Turn off phone before connecting additional devices.
Match cables to correct ports (Ethernet to PHONE/PC ports).
For Bluetooth: Enable in settings, put headset in pairing mode.
Verify connections: Check link lights on Ethernet ports.

Tip: Use Category 5e or higher Ethernet cables for Gigabit performance.

Advanced Features

Supports multiple lines, call forwarding, conferencing, voicemail.

Multiple lines: Press different LINE keys to switch between calls.
Call hold: Press HOLD button during active call.
Conference: During call, press MORE > CONFERENCE, dial second party.
Transfer: During call, press TRANSFER, dial destination, press TRANSFER again.
Voicemail: Press MESSAGES key or dial voicemail access number.
Directory: Access via DIRECTORY button, search by name/number.
Call history: Press HISTORY to view missed, received, placed calls.
Speed dial: Program frequently dialed numbers to speed dial keys.

WARNING! Do not use liquid cleaners on display. Use soft, dry cloth only.

Accessibility Features

Visual alerts: Flashing LED for incoming calls. Audio adjustments: Separate volume controls for ringer, handset, speaker. High-contrast display: Adjustable in settings menu. Hearing aid compatible: Handset meets TIA-1083 standard.

Care & Cleaning

Unplug power before cleaning. Use soft, dry cloth for display and housing. For stubborn stains, dampen cloth with water only.

CAUTION! Do not use abrasive cleaners, solvents, or aerosols. Avoid excessive moisture.

Regulatory Information

FCC Part 15: Class A digital device; complies with limits for business environments. CE marked for European market. RoHS compliant. Copyright © 2024 Cisco Systems, Inc. All rights reserved. For support, visit www.cisco.com or contact Cisco Technical Assistance Center.

Troubleshooting

Symptom	Possible Cause	Corrective Action
No power	PoE/Power adapter	Check Ethernet cable; verify switch provides PoE; try power adapter.
No network	Cable/DHCP	Check cable connections; verify DHCP server; check VLAN configuration.
No dial tone	Registration	Verify extension credentials; check SIP server connectivity.
Poor audio quality	Network/Codec	Check network latency/jitter; verify codec configuration.
Bluetooth not pairing	Distance/Settings	Ensure headset in pairing mode; check Bluetooth enabled on phone.
Display issues	Settings/Power	Adjust contrast/brightness; reboot phone; check power supply.

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

Service: Cisco Technical Assistance Center: 1-800-553-2447; www.cisco.com/support