To set up Stripe billing for a third-party routing subscription such as Twilio and Telnyx, you would typically follow these general steps:

1. Create a Stripe Account: If you don't have a Stripe account, you'll need to create one You can do this by visiting the Stripe website and following their account setup process.

2. Integrate with Twilio andnyx: You'll need to integrate your Stripe account with Twilio and Telnyx. This may involve using the Stripe API to set up recurring billing for your customers who are using Twilio and Telnyx services.

3. Set Up Subscription Plans: Within your Stripe account, you would create subscription plans that align with the services by Twilio and Telnyx. This might include different tiers of service, pricing options, and billing intervals.

4. Utilize Stripe Billing API: You can use the Stripe Billing API to handle the creation, management, and billing of subscriptions. This would involve creating and updating subscriptions, invoices, and managing customer billing details.

5. Customer Onboarding: When a new customer signs up for your routing service, you would collect their billing information and use the Stripe API to set up a subscription for them.

6. Handle Payments and Invoices: Stripe will handle the ongoing billing and payment processing for your customers. It will also generate and deliver invoices as per the subscription terms.

7. Monitor and Manage: It's important to monitor your Stripe account regularly to ensure that subscriptions are being billed correctly and that payments are processed successfully.

Keep in mind that the specific steps for integrating with Twilio and Telnyx may vary based on their individual APIs and. It's also important to comply with any relevant regulations and requirements for handling customer billing information.

If you encounter any issues or need further assistance with any of these steps, feel free to ask for more targeted guidance!