How the pieces fit
Voice agents and their building blocks
Not everything in this directory is a finished voice agent. Some of these are the parts you build one from. Here is what each kind does, and how to read its score, because a great speech-to-text engine and a turnkey phone platform are not the same purchase.
Full platforms 9
A full platform runs the whole call. You bring a script and a phone number, and it handles the three moving parts of any agent: turning speech into text, working out a reply, and turning that reply back into a voice. This is what most buyers want, and it is what the top of our ranking is built for.
See all 9 full platforms in the directoryVoice engines (text-to-speech) 5
A voice engine turns text into speech. It is the voice, not the agent. Feed it words and it speaks them, in whatever tone or accent you pick. On its own it does not answer a phone or hold a conversation, so it scores high on voice quality and range and lower on the call-handling axes. That is the rubric reading it as a component, which is exactly what it is.
See all 5 voice engines (text-to-speech) in the directorySpeech-to-text 3
Speech-to-text does the opposite. It turns what the caller says into text, accurately and fast. It is the ears. Every full agent needs one, but a speech-to-text engine on its own does not speak or decide anything, so it sits near the bottom of our voice scores by design. Read its value score instead: these are some of the cheapest, most reliable parts you can buy.
See all 3 speech-to-text in the directoryDeveloper frameworks 3
A framework is the wiring. It connects the ears, the brain and the voice into a working agent, but you assemble it in code. That makes it powerful and cheap if you have engineers, and the wrong shelf if you do not. Ease of use scores low here on purpose, because the buyer is a developer.
See all 3 developer frameworks in the directoryEnterprise platforms 3
Enterprise platforms are full agents too, sold the enterprise way. Custom-priced, sales-led, and deployed with help rather than a self-serve signup. There is no public rate and the commitments run into six figures, so they are built for big contact centres, not a founder shipping a bot this week.
See all 3 enterprise platforms in the directoryWant to see where each one sits? The full ranking table scores them all on one rubric, and you can filter it by type. The methodology explains how we score. A building block that scores low on voice quality is showing its role as one piece of the stack, not a fault.