I built Ringup to help voice agents recognize repeat callers with just their phone number and charge their saved card in seconds.
I've been asked what makes this lookup possible. Its the newly launched identity APIs from US carriers (T-Mobile, ATT, Verizon) as part of CAMARA project. These set of open source APIs now make it easy for developers to reliably verify identity directly from carriers and is much more robust than sending SMS OTP.
If you're a Voice AI developer or know someone who is, I am offering free credits for 5 users in exchange for any feedback. Try it out.