SIP Phones Features, Definitions, and Terminology

• HD call quality
• Number of SIP(VoIP) Accounts
• Gigabit Ethernet (GbE) 
• Soft Keys and Line keys 
• Touchscreen 
• Display – Color or Greyscale | Screen size | Screen resolution
• Wi-Fi
• Bluetooth
• Voltage/POE

When deciding which phones would work best for your business you should consider some of the following features and prioritize them within your budget.

HD Call Quality

Phones can come with standard or HD call quality. Standard quality is what you have in traditional phones. HD stands for High Definition, and you may be familiar with the term in relation to video displays. In phones, we are only dealing with audio quality, but the concept is similar. HD delivers much better audio quality which sounds much closer to the natural sound of the human voice.

In technical terms, HD call quality has twice as many audio samples as standard sound sampling. It also captures audio frequencies in a much wider spectrum than standard audio, which also contributes to its more natural-sounding qualities.

You should get HD phones if you prefer that your employees and clients communicate with better more natural-sounding voice quality.

Number of SIP(VoIP) Accounts

To use a SIP phone and connect it to a VoIP server you need a SIP account. Your phone number, voicemail, and entire calling activity are associated to this account.  

Most SIP phones allow for multiple accounts to be registered simultaneously. Only one account can actually be active at any given time, but the multiple registrations allow users to easily switch between phone numbers/accounts instead of having to log out/log in to a different account every time they need to switch numbers.

The number of available SIP accounts you may need depends on the number of users that would share the phone. With most phones already offering dozen or more accounts, this is usually not a major consideration for the average business.

Gigabit Ethernet (GbE)

You may notice that some phones have the letter G in their model number.  This stands for gigabit and indicated that they support a one-gigabit data rate. In telecommunication and computer networking, this is a measurement of the amount of data that is transferred in one second between two points.

Most phones have two data jacks, one for connecting to the network and one for connecting to a personal computer. In some office environments there is a limited amount of available data ports and phone data jacks are needed for wiring devices to the network. Unless a device is plugged directly into an Ethernet port, the maximum network speed available to it will depend on the phone’s specification. For example, if you have a one-gigabit computer but your computer is connected to the network via a slower 100 Mbps phone then your computer will only be able to achieve a maximum 100Mbps gigabit network rate.

Another thing to note is that the current popular Wi-Fi 4 standard typically delivers top speeds of up to 500MB per second. If you connect devices wirelessly to a gigabit router you would only be using half of its potential, but for VoIP this speed is more than sufficient and the newer Wi-Fi standards will surpass gigabit performance. 

While VoIP does not require gigabit speeds, you should get gigabit phones if you want to maximize the performance of your office network.

Soft Keys and Line keys

Soft keys are buttons that can perform context and feature dependant functions instead of having fixed operations. Soft keys are usually placed directly adjacent to the screen to allow for easy interaction with the current prompts and available options.

Example: You are editing a contact to the phone’s memory. You have the option to “Save” or “Cancel” associated with two soft keys. If you select to cancel the screen will prompt “Are you sure you want to discard the changes” with the same two soft keys now associated with “Yes” and “No”.

Line keys are buttons that are used for selecting different phone lines and extensions. If they are adjacent to the screen they can also double as soft keys and interact with the content on it. Line keys can have BLF functionality to indicate the presence and availability of other users on the system.

More advanced phones will have customizable soft keys called DSS – Direct Station Selection. These are not necessarily associated with the basic operation of the phone but can be customized to perform various phone and PBX functions. For example, a user can program one DSS key to open the company’s directory and program a different DSS key to forward a call to a specific call queue.

Touchscreen phones usually don't have physical soft keys but offer similar functionality with contextual buttons and icons on the screen itself.

Some of the corded Yealink phones that we sell offer expansion modules that add additional soft and line keys to the phone. See the SIP Telephones Buying Guides article for more details.

You should get phones with more soft and line keys (or ones that can be extended) if you want to have the flexibility to perform more functions and connect with more users directly from the phone itself rather than from a softphone or the TeleConsole.

Touchscreen

A telephone display that allows direct interaction with context, very much like your smartphone or tablet. Touchscreens essentially replace the function of soft keys, making any soft keys on a phone available to be user customized.

You should get phones with touchscreens if you want users to have easier and more intuitive communication. 

Display – color or greyscale

Self-explanatory. This is an indication of the display being color or greyscale. Color displays allow for more details and visual cues (for example active calls can be green and held calls can be red). Color displays are inherently more advanced and therefore usually also have more pixel count, which makes them sharper with more legible icons.