Understanding VoIP Hard Phones

If you can see it, feel it, and tether it with a network cable, and if it includes a traditional phone keypad, you have a VoIP hard phone. Because there are many makes, models, and manufacturers, competition helps lower the price.

Even though you find much diversity, two things should be common to every VoIP (voice over Internet protocol) hard phone: support of transmission control protocol/Internet protocol (TCP/IP) (mandatory for VoIP) and at least one RJ-45 connection port.

The RJ-45 connector on a hard phone is an Ethernet port used to connect the phone to your network. Through this port, your phone can communicate with any other IP-based device on the network. These devices include servers that keep track of everybody's telephone number and voice mail, other VoIP phones, the gateway to the public switched telephone network (PSTN) (for off-net calling), and the router that takes care of establishing a connection to other VoIP phones on the network (on-net calling).

The RJ-45 port looks like a regular phone jack (RJ-11), but it's a little wider. In Figure 1, the jack on the left is an RJ-11 and the one on the right is an RJ-45. It is the jack on the right that you would use to connect this VoIP hard phone to the network.

Figure 1: Connections on the back of a VoIP hard phone.

Hard-phone categories

The VoIP hard phone looks the most like a traditional desk phones. Hard phones can be broadly categorized as basic, intermediate, and advanced phones, based on their capabilities.

• Basic: Basic VoIP hard phones look like a traditional desk phone. The dialing pad is clearly distinguished. This type of phone is considered a basic, entry-level IP phone that delivers good VoIP telephony service. That is, it makes and receives telephone calls over the VoIP network (on-net) or the PSTN (off-net). You could find such a hard phone on the desk of a staff person or in common areas such as the lobby or hallway of any typical company.

• Intermediate: This type of VoIP phone has a large screen and many more hard buttons compared to the basic hard phone. Intermediate phones can do anything that the basic hard phone can do plus more. This phone can often do Web browsing and access the company phone directory.

• Advanced: Advanced models usually include color video displays and multiple telephony-related applications. These phones have fewer hard buttons than intermediate hard phones because the phone's screen and software can enable many more functions than could be manufactured into the phone's chassis.

Focus on features

Telephony features can be delivered in two ways:

• As a function of your VoIP hard phone

• Through the VoIP network to the phone from another device attached to the network, such as a server or a telephone controller

In the older world of telephony (pre-VoIP), features were known as call features, line features, or system features. You paid for these features each month, sometimes on a per-line basis. This may not seem like much in the grand scheme of things, but if you or your company has multiple lines, feature costs can significantly increase your monthly phone bill. In the VoIP telephony world, all features are free.

The VoIP hard phone itself plays a role in exactly what type of features you receive. Its common features (like those on traditional phones) include call holding, conference call, transfer, redial, volume control, mute, and the other usual stuff.

• The basic VoIP hard phone also provides at least two call appearances, the ability of the phone to bring up and maintain separate telephone calls as if you had separate physical lines. Call appearance buttons are usually located near the Hold button and are labeled 1 and 2.

• Intermediate phones usually include a flat screen. Some of the more expensive ones provide limited Web browsing. These hard phones also come with the ability to receive their electric power from the network. This means that the local area network (LAN) can provide the power the phone needs through its network connection. As a result, you don't need to plug in a power cord at your desk.

Traditional features found on any basic VoIP hard phone are provided by buttons on the phone. The intermediate phone usually includes several buttons, but it also has many other features provided through its software and screen.

• Some people refer to advanced hard phones as appliances because they do more than just allow you to carry on traditional voice conversations. For example, they usually provide Web-related features and may include other applications. Advanced VoIP hard phones include all the features found on basic and intermediate phones, plus the following:

• Phone: Allows the advanced phone to use capabilities offered through a telephony server or other telephone system connected to the VoIP network.

• Directory: Provides access to the corporate LDAP (lightweight directory access protocol) server on the network. With this type of access, you don't have to even dial the number. You can look up the name on the LDAP and press one button; the network takes care of the rest.

• Web access: Advanced hard phones have expanded access that is closer to what you might expect from the browser on your computer. Web access capability often includes support for Java applets (self-contained programs created in the Java language).