VoIP (Voice over Internet Protocol) is a general term for technology that enables voice calls over internet connections. While traditional PSTN (Public Switched Telephone Network) transmits analog voice signals over copper cables, VoIP converts voice into digital data and sends/receives it as IP packets over the internet. The majority of modern telephone communications use VoIP technology in some form.
Understanding the precise difference from IP phones is important. VoIP is the general term for the technology, while IP phone is one form of telephone service that uses VoIP technology. 050-number IP phones, Hikari Denwa, LINE calls, Skype, Zoom, FaceTime, and WhatsApp all use VoIP technology, but LINE calls and Zoom, which don't have phone numbers, are not called IP phones. VoIP is the technology; IP phone is the service.
The greatest advantage of VoIP is low call costs. With an internet connection, calls can be made at no additional cost, and international calls are very affordable. For businesses, combining VoIP with cloud PBX can eliminate inter-office extension call charges and dramatically reduce telephone infrastructure costs. Calls are controlled via the SIP protocol, with voice compressed and transmitted using codecs.
Disadvantages include call quality being dependent on internet connection quality. Insufficient bandwidth causes packet loss and voice interruptions. High latency disrupts conversation rhythm. QoS configuration to prioritize voice packets is essential. Additionally, during power outages, internet equipment stops working, making calls impossible. Emergency call support also has limitations, as 050-number IP phones cannot reach emergency services. Review technical details in VoIP basics and benefits.