Cisco CP-7821-K9 Full English Product Description

Listing Title

Cisco CP-7821-K9 Unified Two-Line IP Desk Phone (Dual CUCM SCCP / MPP 3PCC Open SIP Firmware), 3.5-inch Backlit Monochrome 396×162 LCD Display, Dual 10/100BASE-TX Fast Ethernet Switched Ports with PC Pass-Through, IEEE 802.3af Class 1 PoE Powered, G.722 HD Wideband Full-Duplex Echo-Canceling Speakerphone, Dedicated Hold / Transfer / Conference Fixed Hard Keys, RJ9 Analog Headset Port, HAC Hearing-Aid Compatible Handset, Low-Power Eco Operation, Textured Charcoal Black ABS Chassis, Removable Silver Bezel Optional Upgrade, Two-Position Adjustable Desktop Stand, Wall Mountable (Wall Kit Sold Separately), Ideal for General Office Staff, Clinic Receptionists, Small Business Back-Office Employees and Medium-Traffic Two-Line Business VoIP DeploymentsCisco

Full Commercial Overview

The Cisco CP-7821-K9 is the mid-tier two-line VoIP endpoint within Cisco IP Phone 7800 Series, engineered for daily general office employees requiring dual independent directory number (DN) multi-call support and full visual LCD call management. The platform supports dual firmware modes: native SCCP (Skinny Client Control Protocol) for on-prem Cisco Unified Communications Manager (CUCM/CUCM Express), and Multiplatform (MPP) 3PCC open SIP firmware fully compatible with Webex Calling, BroadWorks, Zoom Phone and all third-party hosted SIP PBX systems.

Core differentiators vs entry-level CP-7811 single-line model: two programmable tricolor LED line keys for dual DN support, larger high-resolution 3.5-inch LCD screen, expanded shortcut keys for directory, messages and applications, and higher daily multi-call handling capacity for medium-traffic office workflowsCisco. Optional cosmetic upgrade: interchangeable silver front bezel to replace the standard charcoal black chassis for modern office aesthetic customization.

The unit adopts durable textured recyclable polycarbonate ABS chassis construction, ultra-low Class 1 PoE power consumption (max 3.84W) with configurable LCD backlight timeout to cut off-hours energy costs, and an adjustable two-angle foldable desktop foot stand for ergonomic screen viewing. Vertical wall installation requires a separate optional wall-mount accessory kit, with pre-designed rear chassis cutouts for secure mounting.

Cisco announced End-of-Sale (EoS) for the entire 7800 Series on May 8, 2026, with final hardware order cutoff set for October 28, 2026; limited critical security and bug maintenance support will continue through the published hardware lifecycle timeline, with no new feature firmware development planned. All remote mass provisioning, unattended bulk firmware upgrades and centralized device monitoring are supported via TFTP/HTTP/HTTPS secure auto-provisioning servers and embedded HTTPS web administration portal, fully integrated with CUCM and cloud third-party UCaaS voice platforms.

Hardware & Physical Design Architecture

1. Ergonomic Chassis & Mounting Options

• Form factor: Compact low-profile desktop body equipped with a two-position adjustable foldable foot stand delivering optimized LCD viewing angles for different desk layouts. The foot stand can be fully detached; wall mounting requires separate optional wall-mount kit with dedicated rear chassis mounting cutouts.
• Chassis material: Textured matte black recyclable polycarbonate ABS plastic; interchangeable silver decorative front bezel available as a separate cosmetic upgrade accessoryCisco.
• Physical Dimensions (H × W × D, excluding foot stand and handset): 207mm × 206mm × 28mm
• Total Unit Weight (including standard coiled handset): 867 grams
• Operating Environment (Indoor Use Only): Operating Temperature: 0°C ~ +40°C (32°F ~ 104°F) Storage Temperature: -10°C ~ +60°C (14°F ~ 140°F) Operating Humidity: 10% – 90% non-condensing Storage Humidity: 10% – 95% non-condensingCisco

2. Key Layout, LCD Display & Control Hardware

The CP-7821 features a large high-resolution backlit monochrome LCD paired with streamlined fixed-function hard keys and two programmable BLF line keys optimized for dual-line daily office workflows:

1. Backlit monochrome LCD display: 3.5-inch diagonal screen, 396 × 162 pixel resolution, adjustable screen contrast and backlight brightness; displays color-coded Caller ID name/number, real-time call timers, local call history logs, personal/corporate directory entries, system menu navigation, date/time clock, dual-line status indicators and voicemail MWI alertsCisco.
2. Dual tricolor LED illuminated programmable line keys: Visual real-time line state signaling for two independent DNs (solid green = idle line; solid red = active/held call; flashing red = incoming ringing call); keys support BLF status monitoring for shared extensions or colleague line presence tracking.
3. Three dedicated one-touch fixed function hard keys: Hold, Transfer, Conference for instant call control without multi-layer menu navigation.
4. Standard 12-key tactile backlit numeric dial pad (0–9, *, #) with high-contrast backlit keys for low-light office visibility.
5. Three context-sensitive softkeys positioned directly below the LCD screen, dynamically mapped to on-screen menu options.
6. Central five-way directional navigation rocker with integrated select button for scrolling contact directories, call logs and device configuration menus.
7. Auxiliary dedicated shortcut hard keys: Mute, Headset, Volume Up/Down rocker, Redial, End Call, Messages, Applications, Directory one-touch shortcut keys.
8. Vertical red Message Waiting Indicator (MWI) LED on the top chassis edge to notify users of unheard voicemail messages.

3. HD Wideband Audio Subsystem & Supported Codecs

• Ergonomic analog coiled handset with noise-isolating receiver, certified HAC (Hearing-Aid Compatible) to meet global accessibility standards for users wearing hearing assistive devices.
• Built-in full-duplex echo-canceling hands-free speakerphone optimized for G.722 HD wideband voice clarity, with automatic DTMF tone masking during speakerphone operation for call privacy.
• Dedicated RJ9 modular analog headset port supporting all standard wired office headsets for long-duration private calls.
• Supported voice audio encode/decode codecs: G.722 HD wideband audio, G.711a / G.711u narrowband, G.729a, iLBC low-bitrate codec.
• Voice quality optimization features: Voice Activity Detection (VAD), Comfort Noise Generation (CNG) to eliminate artificial silent line background noise during idle call periods.

Network, Power & Hardware Interfaces

1. Dual 10/100BASE-TX Fast Ethernet Switched RJ45 Ports

Two auto-sensing Fast Ethernet ports with integrated mini internal network switch, enabling seamless daisy-chaining of desktop PCs without additional wall-mounted network jacks, reducing office cabling infrastructure costsCisco:

• Primary WAN Network Port: Connects the IP phone to corporate LAN switches, VoIP gateways or SIP PBX servers for SIP/SCCP call control signaling and RTP voice media data streams.
• Secondary PC Pass-Through Port: Provides direct wired network connectivity for attached laptops, desktop workstations or POS terminals routed through the phone’s integrated switch.

Supported networking standards: IPv4 addressing only (DHCP dynamic IP assignment or static manual IP configuration), Cisco Discovery Protocol (CDP), LLDP-MED device discovery, 802.1Q voice VLAN tagging, 802.1p Layer 2 QoS traffic prioritization, STUN NAT traversal for remote worker deployments, SNTP network time synchronization.

2. Dual Power Supply Options (Class 1 PoE Primary Power)

1. Native IEEE 802.3af Class 1 Power over Ethernet support (primary power source): Maximum typical power consumption: Only 3.84 watts for ultra-low idle energy draw, configurable screen backlight timeout to further reduce power usage during off-hours. Input rating: 48V DC PoE power input from all compliant IEEE 802.3af PoE network switches.
2. Optional auxiliary external 48V DC universal AC-to-DC power cube (part number CP-PWR-CUBE-3=, sold separately) for non-PoE network environments lacking PoE-enabled switches.

3. Rear Panel Physical Interfaces

1. RJ9 modular handset jack for connecting the coiled handset cord
2. Dual RJ45 10/100 Fast Ethernet PoE switched ports (Network uplink + PC pass-through)
3. RJ9 analog headset audio jack
4. DC 48V auxiliary power input jack for optional external power adapter
5. Recessed pinhole password-protected factory reset button to restore all device firmware and configuration settings to factory default values

Core Telephony Feature Set

All calling and device configuration functions are provisioned via CUCM / third-party SIP PBX auto-provisioning templates; routine call operations are triggered via dedicated physical hard keys or LCD softkey menu navigation:

1. Dual-Line Multi-Call Handling Supports two independent directory number (DN) line registrations with multi-call-per-line appearance, allowing multiple concurrent active calls on each line plus native call waiting functionality. Dedicated Hold key for call park, dedicated Transfer and Conference hard keys for one-touch consultative transfer and three-way ad-hoc audio conference calls. Supports call swap between multiple active calls, automatic last-number redial via dedicated Redial key. Dual line keys support BLF presence monitoring for shared extensions or co-worker line status tracking.
2. Caller ID & Personalization Features Visual Caller ID name and number display on the backlit LCD screen; adjustable ringtone volume and multiple selectable distinct ringtone tones, customizable unique ring alert patterns for incoming internal vs external calls. On-device local directory storage with search functionality, plus XML framework support for corporate LDAP enterprise directory lookup and XML hosted application rendering.
3. Utility Workplace Calling Functions One-touch redial, mute hard key for confidential private conversations, dedicated headset mode toggle, shared line appearance monitoring support for multi-user shared reception lines, call forward all/busy/no answer, call park and call pickup functionality, intercom auto-answer calling for internal facility staff communication.
4. Local Call Log Storage Onboard persistent flash memory storage for dialed outgoing calls, received answered calls and missed incoming calls, complete with timestamp, call duration and full Caller ID details; all logs fully viewable directly on the phone’s LCD screen or embedded web management portal. The device stores up to 24 entries each for dialed, received and missed call records.
5. Voicemail MWI Integration Native Message Waiting Indicator (MWI) notification delivered via SIP/SCCP SUBSCRIBE/NOTIFY messaging; steady red chassis MWI LED illumination plus on-screen LCD pop-up visual alerts to notify users of unheard voicemail messages, with dedicated Messages shortcut key for one-touch voicemail retrieval.
6. Supported Security Call Features Anonymous incoming call rejection, outbound caller ID blocking configurable via PBX/server-side settings, end-to-end encrypted SIP/SCCP call control signaling (TLS 1.2) and encrypted voice media streams (SRTP AES encryption) for secure communications on shared corporate LAN networks.

Security & Remote Device Management Capabilities

1. End-to-End Encrypted Voice & Signaling Communications TLS transport layer encryption for all SCCP/SIP call setup and control signaling; SRTP AES encrypted RTP voice media data streams to prevent unauthorized wireless or wired call audio interception on shared office network infrastructures. The platform supports AES-128 and AES-256 encryption algorithms for both signaling and media traffic.
2. Multi-Tier Access Permission Controls Separate administrator and end-user access privilege levels protected by unique alphanumeric authentication passwords; password-locked factory reset function to block unauthorized wiping of device line registrations, directory contacts and configuration data.
3. Centralized Auto-Provisioning & Unattended Firmware Upgrades Fully unattended remote bulk firmware upgrades pushed via TFTP/HTTP/HTTPS secure auto-provisioning servers, fully compatible with CUCM, CUCM Express and third-party SIP/UCaaS platforms including Webex Calling, BroadWorks and Zoom Phone. Embedded HTTPS web-based local administration portal for on-site device configuration and real-time status monitoring.
4. System Monitoring & Built-In Network Diagnostics Real-time device status tracking available via CUCM / third-party SIP PBX management consoles, including online/offline LAN connectivity status, SIP/SCCP line registration state, active call session auditing and centralized syslog event logging for complete network telephony audit trails; integrated built-in ping and traceroute diagnostic tools for network connectivity troubleshooting. The phone also supports IEEE 802.1X network access authentication for enterprise LAN security enforcement.

Environmental & Regulatory Compliance Certifications

• Regulatory EMI/EMC: FCC Part 15 Class B electromagnetic interference compliance, CE marking for European Union market compliance, AS/NZS CISPR22 Class B certificationCisco.
• Safety certifications: UL / C-UL 60950 Second Edition electrical safety certification, EN 60950 Second Edition (including A11 and A12), IEC 60950 Second Edition (including A11 and A12), AS/NZS 60950, GB4943 China national safety standardCisco.
• Telecom regulatory approvals: FCC Part 68 telecom terminal device certification, TIA 810A HAC hearing aid compatibility standard.
• Memory architecture: 8MB flash memory for persistent firmware, directory and configuration storage; 32MB SDRAM runtime memory for SCCP/SIP call processing, LCD screen rendering and network stack operation.
• Lifecycle Status: Announced End-of-Sale (EoS) May 8, 2026, final hardware order deadline October 28, 2026; limited critical security/bug maintenance support only, no new feature firmware development.
• Warranty: Standard one-year limited Cisco hardware warranty for commercial business end-user deployments.

Key Specification Bullet Points

• Model Number: Cisco CP-7821-K9 (Charcoal Black Two-Line Unified IP Phone; Silver decorative bezel sold separately as upgrade accessory)
• Device Type: Mid-Tier Two-Line Unified IP VoIP Desk Phone (Dual Native CUCM SCCP / MPP 3PCC Open SIP Dual Firmware), Backlit Monochrome LCD Display, Dual Switched Fast Ethernet Ports with PC Pass-Through
• Supported Telephony Protocols: SCCP (Skinny Client Control Protocol) + SIP v2 for Cisco CUCM / UCME; MPP Multiplatform 3PCC SIP v2 open standard for third-party SIP PBX / Webex Calling / Zoom Phone / BroadWorks UCaaS platforms
• Supported Voice Audio Codecs: G.722 HD Wideband Audio, G.711a / G.711u, G.729a, iLBC Low Bitrate Codec
• Display: Backlit Monochrome LCD Screen, 3.5-inch diagonal, 396 × 162 Pixel Resolution, Adjustable Contrast & Backlight Brightness, Multi-Language Menu Support
• Fixed Hardware Function Keys: Dual Programmable BLF Line Keys, Dedicated Hold, Redial, Transfer, Conference, Mute, Headset Hard Keys; Three Dynamic LCD Softkeys, Five-Way Navigation Rocker, One-Touch Shortcut Keys for Messages, Applications, Directory
• Audio Features: HAC Hearing-Aid Compatible Handset Receiver, Full-Duplex Echo-Canceling HD Wideband Hands-Free Speakerphone, VAD Voice Activity Detection, CNG Comfort Noise Generation, RJ9 Analog Headset Port
• Physical Interfaces: 1 x RJ9 Handset Port, Dual 10/100BASE-TX RJ45 Fast Ethernet Switched PoE Ports (Network Uplink + PC Pass-Through), RJ9 Headset Jack, 48V DC Aux Power Input Jack, Password-Protected Factory Reset Pinhole
• Power Specifications: IEEE 802.3af Class 1 PoE Primary Power, Max Typical Power Consumption 3.84W, Configurable Backlight Timeout Energy-Saving Mode; Optional Separate 48V DC Universal AC Power Cube (CP-PWR-CUBE-3=, Sold Separately)
• Mounting Method: Adjustable two-position foldable desktop foot stand as standard; Wall mountable via separate optional wall-mount accessory kit
• Supported QoS & Networking Features: IPv4 DHCP/Static IP Assignment, CDP/LLDP-MED Device Discovery, 802.1Q Voice VLAN Tagging, 802.1p Layer 2 QoS Prioritization, STUN NAT Traversal, SNTP Network Time Synchronization, IEEE 802.1X Port-Based Network Authentication
• Security Features: TLS 1.2 Encrypted SCCP/SIP Call Signaling, SRTP AES 128/256 Encrypted Voice Media Streams, Dual-Level Admin/User Password Access Control, Password-Locked Factory Reset, Embedded HTTPS Web Administration Interface
• Core Telephony Call Features: Two Independent SIP/SCCP Line Registrations with BLF Presence Monitoring, Multi-Call-Per-Line Appearance, Supports Multiple Concurrent Calls + Call Waiting, Dedicated Hold / Redial / Transfer / Conference Hard Keys, Full-Duplex HD Wideband Speakerphone, Visual LCD Caller ID Display, MWI Voicemail Message Waiting LED Alert, Anonymous Call Rejection, Outbound Caller ID Blocking, Shared Line Appearance Support, Call Forward, Call Park & Call Pickup, Local Stored Call Logs (24 entries each for dialed/received/missed), XML LDAP Corporate Directory Lookup, XML Hosted Application Rendering, Intercom Auto-Answer Calling
• Management Tools: TFTP/HTTP/HTTPS Secure Remote Auto-Provisioning, Unattended Bulk Remote Firmware Upgrades, Embedded Web-Based Local Admin Portal, CUCM / Third-Party SIP PBX Centralized Device Monitoring, Syslog Event Logging, Built-In Ping/Traceroute Network Diagnostic Tools
• Target Deployment Scenarios: General small and medium business office staff desks, retail store supervisory back-office workstations, clinic and dental practice multi-line reception counters, medium-traffic two-line daily office voice deployments, hotel administrative staff dual-line auxiliary phones, all routine business VoIP environments requiring dual independent multi-call lines, visual LCD call management and dedicated physical transfer/conference hard keys
• Lifecycle Status: Announced End-of-Sale (EoS) May 8, 2026, final hardware order deadline October 28, 2026
• Warranty: One-year limited Cisco hardware warranty

Model Quick Reference

• CP-7821-K9 is the mid-tier two-line IP phone of Cisco IP Phone 7800 Series, supporting dual CUCM SCCP/SIP and open MPP 3PCC third-party SIP firmware, purpose-built for daily general office employees requiring dual independent multi-call lines and full visual LCD call management functionality.
• Core positioning: Balanced cost and productivity two-line business VoIP endpoint with large high-resolution backlit monochrome graphical LCD display, differentiated from the entry-level single-line CP-7811 model by dual programmable BLF line keys for two independent DNs, expanded shortcut keys for directory/messages/applications and higher daily multi-call handling capacity for medium-traffic office workflows.
• Key internal series differentiation vs other 7800 series models:
  1. CP-7811-K9: Single independent line only, no BLF line key bank, smaller low-resolution LCD screen, basic shortcut key layout
  2. CP-7821-K9: Dual independent multi-call lines with BLF presence monitoring, large high-res 396×162 LCD screen, expanded dedicated shortcut keys for directory, messages and applications
  3. CP-7841-K9: Four-line high-capacity executive model, expanded bank of programmable BLF line keys for four DNs, identical LCD screen specification as 7821
  4. CP-7861-K9: 16-line flagship high-capacity reception/executive model, large multi-column BLF programmable key panel for up to 16 directory numbers
• Primary deployment advantage: Balanced mid-tier productivity and cost efficiency for daily general office staff, combining two independent multi-call lines with BLF colleague presence monitoring, sharp high-resolution LCD visual Caller ID and directory management, dual Fast Ethernet switch eliminating extra wall jacks for attached office PCs, dedicated physical Transfer/Conference hard keys to simplify routine multi-call workflows, ultra-low Class 1 PoE power consumption with configurable backlight energy-saving mode, flexible desktop or optional wall mounting, and dual firmware compatibility supporting both on-prem CUCM and cloud third-party UCaaS voice platforms.

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