An IP phone is a device that enables voice calls to be transmitted over the internet instead of through traditional telephone lines. It has the capability to convert analog voice signals into digital data packets, allowing for clear and reliable communication. IP phones are often equipped with features such as caller ID, call waiting, voicemail, and conference calling. They can be used in conjunction with a VoIP service provider to make calls to both landlines and other IP phones. Overall, IP phones offer a cost-effective and convenient solution for modern communication needs.