Asterisk is a free open-source framework for building customized communications applications, such as VoIP gateways and IP PBX systems.
bvoip is a channel-only VoIP service provider that offers a scalable cloud-based UC tool. Its solution and prices are customized.
ClarityTel is a VoIP provider that offers cloud-based telephony solutions. It costs $24.99 per line, per month for those who need one to nine lines.
Comcast Business is a VoIP provider that offers private branch exchange (PBX) trunking and cloud-based phone solutions.
1-VoIP offers residential, business, and SIP trunking services. Business VoIP plans have monthly base fees that range from $14.97–$29.97+/extension.
2Talk is a VoIP provider that offers cloud-based PBX solutions. It has monthly fees that range from $9.95 to $350, depending on the inclusions.
3CX is a VoIP provider that offers on-premise and cloud-hosted phone system solutions. Annual fees range from $0 to $39,990 per year.
Aircall is a VoIP provider that offers cloud-based business phone systems. Its annual-billed fees range from $30 to over $50 per user per month.
8×8 is a suite of VoIP solutions that help users communicate with their customers over voice and video. Prices start at $12 per user per month.
FluentStream is a VoIP platform that allows users to connect with their customers through a unified suite. Fees range from $5 to $20+/user/month.
Truly is a Voice over Internet Protocol (VoIP) provider that offers local and international calling and conversation intelligence solutions.
Acquisio offers pay-per-click management tools, including a search engine marketing software. Its monthly fees reportedly range from $199 to $1,899.