**Which device is commonly used for IP telephony communications?**
A **VoIP phone** (Voice over Internet Protocol phone) is commonly used for IP telephony communications. These devices convert analog voice signals into digital data packets, enabling voice communication over the Internet. VoIP phones can be hardware-based, resembling traditional telephones, or software-based, functioning as applications on computers or mobile devices. By utilizing an IP network, VoIP phones often provide cost advantages, especially for long-distance calls, and additional features like video conferencing, voicemail, and call forwarding. They are integral to modern telecommunication systems in both business and personal contexts.