FreeSWITCH vs Plivo Voice API

FreeSWITCH is an open-source framework for real-time voice and video communications. It can route calls, bridge video, transcode media, and connect protocols, and is designed for use in carriers, contact centers, and communication products. Its Event Socket exposes call control, channel management, and internal events to external processes over TCP. Integrations include HTTP backends, embedded Lua, Perl, Python, JavaScript, Java, and SignalWire connectivity. The mod_signalwire module connects to SignalWire for inbound and outbound PSTN calling over a persistent WebSocket session. Linux installation guidance covers Debian and Ubuntu using SignalWire packages or a source build. A free SignalWire account is required to access packages and downloads. FreeSWITCH is licensed under MPL 2.0 and can run in production at no cost; self-hosting requires dedicated resources to maintain on-premises infrastructure. The open-source edition has community support, while FreeSWITCH Pro offers commercial support, hardened builds, priority patches, and commercial modules including answering machine detection and licensed G.729 Annex A encoding and decoding.

Plivo Voice API lets web and mobile applications make and receive calls programmatically, play audio, record conversations, and build interactive voice applications. It connects calls across PSTN, SIP, and WebRTC endpoints. Features include queues, conferences, text to speech, dual-channel recording, DTMF input, speech recognition, answering machine detection, voicemail transcription, and custom caller ID. Its Audio Streams API sends raw audio from active calls over WebSocket for transcription, voice AI, analytics, or custom processing. Plivo lists SDKs for Python, Node.js, Ruby, PHP, Java,.NET, and Go, along with integrations including Zapier, n8n, Pipedream, Tray, EngageBay, and Microsoft Power Automate. The service is listed for Android, iOS, web, and API. The Voice API pay-as-you-go plan is listed at $0.01 a month; call routes and features have separate rates. Calls are billed in 60-second increments. Pay-as-you-go accounts receive $10 in free credits without a credit card. Plivo was founded in 2011 and is headquartered in Austin, Texas.