What Are Virtual Phone Numbers?

IP desk phones, or SIP devices, plug into routers/modems instead of phone jacks. They connect via Ethernet, making them highly portable. Unlike landline systems, you need not install IP desk phone lines.

SIP devices look like traditional phones. However, some models carry hotkeys—buttons for fast access to PBX features. Common hotkeys include redial, transfer, hold, and menu.

Some phones offer more built-in features than others and some come with added hardware. For example, you can find SIP devices with wireless network cards and conference speakers.

•  Wi-Fi phones resemble mobile phones more so than desk phones. With them, you can walk around freely within the radius of a given local network. They often come with fewer features than their desktop counterparts, but they improve portability.
•  Conference phones have high microphone/speaker performance for group usage. Unlike desktop phones, users talk at the device rather than into it. It's like speaker mode on other phones—only crisper, clearer, and without feedback.

Softphones are voice applications for computers. They work like ordinary SIP phones but rely on input devices (i.e. mouse and keyboard) and headsets or microphones. Softphones are the cheapest way to connect to an online phone system—most are free!

•  Headsets allow workers to take and place calls hands-free. They connect in various ways: USB, Bluetooth, or audio jack. Most promise a “plugin and play” experience. Simply connect to your device and launch the softphone—no lengthy installations.
•  Smartphone apps exist for online calling. They work like desktop softphones over cellular data.

All landlines can receive phone calls. However, to place calls, you need an Analogue Telephone Adapter (ATA). ATA boxes convert landline signals into digital ones. They are a type of bridge between PSTN and data networks.

Note that upgrading an analogue phone system can be costly. Since entry-level SIP devices are rather inexpensive, replacing old hardware may be more cost-effective.

•  Expansion Modules: Some SIP devices support external hotkey panels known as expansion modules. Such devices are compatible with only specific models and manufactures.
•  Wall Mounts and Foot Stands: Wall mounts hang devices as you might with a traditional phone. Foot stands tilt devices forward. Plus, they connect can many phones and modules together.
•  Uninterruptible Power Supplies (UPS): UPS devices protect against power surges and failures. Plugin your networking gear, phones, and computers into one or more UPS devices and enjoy hours of backup calling.