A VoIP phone is a hardware or software-based telephone designed to use voice over IP (VoIP) technology to send and receive phone calls over an IP network, such as the internet, rather than the traditional public switched telephone network (PSTN).

There are two main types of VoIP phones:

1. Hardware-based VoIP Phones: These look like traditional telephones but are equipped with specialized hardware to support IP technology. They connect directly to your router via Ethernet or wirelessly and are configured specifically for VoIP communication.
2. Software-based VoIP Phones: Often referred to as "softphones", these are software applications installed on a computing device, such as a PC, laptop, tablet, or smartphone. Softphones use the device's internet connection and built-in audio hardware (or external microphone and speakers) to place and receive VoIP calls. Examples include Skype, Zoom, and the voice-calling feature of WhatsApp.

Key features of VoIP phones include:

• Codec Support: VoIP phones use codecs to convert voice into data packets and vice versa. Some common codecs include G.711, G.722, and G.729.
• Call Features: Many VoIP phones come with advanced call handling features, such as call transfer, call hold, call conferencing, voicemail, caller ID, and more.
• Network Configuration: These phones often have capabilities to connect to different types of networks, be it via Ethernet, Wi-Fi, or even cellular networks when using softphones on mobile devices.
• HD Voice: Many modern VoIP phones offer high-definition (HD) voice capabilities, providing clearer audio quality compared to traditional phone calls.
• Integrated Directories: VoIP phones can integrate with directory services, allowing users to access contact lists or directories to quickly place calls.
• Power over Ethernet (PoE): Some hardware-based VoIP phones can receive power and data through the same Ethernet cable, eliminating the need for a separate power adapter.
• Security Features: Given that VoIP calls traverse the internet, VoIP phones often incorporate security features such as encryption and secure boot to protect calls from eavesdropping and tampering.

VoIP phones, both hardware and software varieties, have gained popularity in businesses and homes because of the cost savings, flexibility, and enhanced features they offer when compared to traditional landline phones.