Rime, a San Francisco-based startup, just raised $24 million to make AI-powered customer service calls feel less like a robotic dead end and more like a real conversation. Unlike competitors scraping the web for audio data, Rime builds its own voice models from scratch—trained on proprietary recordings to better handle brand names, industry jargon, and natural speech.

How Rime’s voice AI stands out in a crowded field

Most enterprises still rely on clunky IVR systems because today’s voice AI often feels like a fancier version of the same old automated menu. Rime’s founders—a team of Stanford engineers and ex-Amazon Alexa talent—are betting on a different approach: phoneme-based models that adapt to pronunciations without requiring clients to retrain the system for their industry. Think of it like teaching a new employee the lingo once, rather than repeating it for every department.

The startup initially used separate models for speech-to-text, text-to-speech, and language processing. Now, it’s pivoting to unified speech-to-speech models to cut latency, improve real-time responses, and filter out background noise—all while reducing the need to juggle multiple systems. Early adopters in healthcare (Mayo Clinic), fintech (Upstart), and telecom (Asurion) report longer, more productive calls, a key selling point for enterprise contracts.

Funding and the road ahead

M13 Ventures led the $24 million Series A, with participation from Twilio Ventures, Corazon Capital, and Unusual Ventures. The funds will expand Rime’s 35-person team, focusing on model development and partnerships. A recent hire, Rafael Valle (formerly of Meta and NVIDIA), joins as Chief Scientist to push the technical edge.

Investors like M13’s Morgan Blumberg argue Rime’s focus on low-latency, high-reliability models—rather than just orchestration—gives it an advantage. While rivals like ElevenLabs and Sierra battle for the application layer, Rime is doubling down on the core tech. The company previously raised $5.5 million in seed funding last May, with Blumberg now joining its board.