Feature	Benefit
Hardware
Ergonomic Design	Highly usable and intuitive arrangement of lines, features and calls. Transfer, Conference and Hold appear on hard keys to reduce the number of presented softkeys to a maximum of 4 per call state.
Customization	This model can be ordered as Arctic White or Charcoal Gray. Handsets are available internationally as slimline (5oz, 140g) or standard (6oz, 170g) and can be mixed and matched between users within the same work environment to enable a feeling of customization and ownership among the users.
Display	VGA presentation for calling, video calling and applications. 5-inch (10 cm) graphical TFT color display, 24-bit color depth, 640 x 480 effective pixel resolution, with backlight. Display also supports localization requiring double-byte Unicode encoding for fonts.
Ethernet	Internal 2-port Cisco Ethernet switch allows for a direct connection to a 10/100/1000 BASE-T Ethernet network through an RJ-45 interface with single LAN connectivity for both the phone and a colocated PC. System administrator can designate separate VLANs (802.1Q) for the PC and phone, providing improved security and reliability of voice and data traffic.
Bluetooth	Mobility for headset users within 30 feet of their desktop to enable the freedom to go to the printer, a colleague's desk or nearby private location while on a call. The 9951 supports the Hands-free and Headset Bluetooth profiles.
USB	2 USB ports accelerate the usability of call handling and applications by enabling accessories such as the Cisco Unified IP Camera, wired and wireless headsets.
External Audio Ports	General Purpose Audio In and Audio Out ports enable a relaxed speakerphone experience over external speakers and microphone.
5 Lines Expanding to 77 with 2 Key Expansion Modules	The convenience of many speed dials or programmable features, or the necessity of following the activity of many lines. Up to 200 calls supported per device.
Buttons	5 feature buttons with state indicating LEDs 5 call session buttons with state indicating LEDs Applications, Directories, Voicemail Conference, Transfer, Hold Volume Up/Down Back-lit Mute, Speakerphone, Headset Back, End Call, 5-Way Navigation Pad Arabic keypad
Accessories
Key Expansion Module	Available separately, enables advanced use of lines, speed dials and features.
Cisco Unified IP Camera	Available separately, enables 2-way video calling between phones or to a media conference unit.
Headset Support	Integrated design & advanced, updateable firmware for Jawbone ICON for Cisco Bluetooth headset which also works with all major mobile phone models. Also supports standard Bluetooth and USB headsets supported via the hands-free and headset Bluetooth profiles. Wideband analog headset support also provided via a dedicated RJ9 headset port on the rear of the phone.
Firmware
New User Experience	Advanced organization of lines, speed dials and programmable features separate from call appearances. Great for those who make few calls per day, better for those who handle dozens of calls per hour.
SIP Signaling	SIP interoperation with the call control and partner applications enables a rich unified communications solution.
Application Support	XML applications provided by Cisco's application development partners or customers' own development staff.