Vapi helps developers build, test, and deploy voice agents at scale. We enable everything in between the raw models and production, including telephony, test suites, and real-time analytics.
Try this step: Go to your Vapi billing page and look for the option to "Switch to Credit Based Billing." Click it if available, then attempt your purchase again. If the issue persists, double-check that your payment method is saved correctly, or try re-adding it. This step is recommended in the Vapi support documentation for similar credit purchase issues.