The Call Stack covers the companies building AI agents that make and receive phone calls — voice agent platforms, the speech and synthesis layers beneath them, the telephony and orchestration infrastructure that carries them, and the analytics and testing tools that keep them honest.
We deliberately stay narrow. We cover AI voice agents operating over real phone lines (the PSTN and SIP) and the infrastructure that serves them. We do not cover general-purpose voice AI, smart-speaker apps, or in-app voice features unless they intersect with AI calling.
How we work
Every news item cites and links its primary source. We check claims — company names, dollar amounts, and named people — against the source material before publishing, and we don't publish what we can't tie back to a source.
When we get something wrong, we fix it in the open. Corrections are noted on the item, edits to published items are kept in revision history, and retracted items stay at their original URL with a clear retraction notice and the reason.
The company index
Companies are added to the index by hand — never automatically. Funding figures, valuations, and headcounts carry their source where one exists, and are marked as estimates when they aren't from a disclosed announcement.
Contact
Corrections, tips, and additions: [email protected].