Voice over IP - Wikipedia
https://en.wikipedia.org/wiki/Voice_over_IP
Voice over Internet Protocol (VoIP), also called IP telephony, is a method and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol (IP)...
Best VoIP Service Providers: 2021 Pricing, Reviews, Guides | GetVoIP
https://getvoip.com/
VoIP Provider comparisons and reviews from real users. Use our data driven guides to find the best VoIP phone service providers and phone systems for your specific needs.