@Aryan N
It sounds like you might have reached the spending limit on your Twilio trial account, which is why you're receiving the message about being "over billing limit." Twilio provides a certain amount of free credit for trial accounts, and once you've used that up, you'll need to upgrade to a paid account to continue using their services.
To resolve this issue, you should log in to your Twilio account and check your usage to confirm if you've exceeded the trial credit. If you have, you'll need to add a payment method and choose a pricing plan that suits your needs to continue using Twilio's services without interruption.
If you believe there's been a mistake or if you need further assistance with your Twilio account, it would be best to contact Twilio's support directly. They can provide more detailed information about your account status and guide you through any necessary steps.
If you need help with anything else or have more questions about the VAPI, feel free to ask!