### Answer --- The

no_valid_payment

disconnection reason indicates that a call was disconnected because there was no valid payment method available to cover the call costs [(1) ]() . This is one of the standard disconnection reasons tracked by Retell AI's system . When a call ends with this reason, it means the account didn't have sufficient credits or a valid payment method configured to complete or continue the call . To resolve this, you'll need to ensure your Retell AI account has: - A valid payment method on file - Sufficient credits or balance to cover call costs You can check the

disconnection_reason

field in your call details via the Get Call API or through webhook events to confirm this was the cause .

​ To learn more, see the sources I considered: [[1] List Calls](https://docs.retellai.com/api-references/list-calls) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.

### Answer High-volume calls can be limited by two main factors: CPS (Calls Per Second) limits and concurrency limits. CPS (Calls Per Second) Limits [(1) ]() CPS controls how many outbound calls you can initiate per second . This prevents system overload and ensures call quality . The default and maximum CPS limits vary by provider : - **Twilio**: Default 1 CPS, Maximum 5 CPS (changes take up to 10 minutes) - **Telnyx**: Default 1 CPS, Maximum 16 CPS (instant updates) - **Custom Telephony**: Default 1 CPS, Maximum = Concurrency ÷ 20 Exceeding these limits results in rejected calls . Concurrency Limits [(2) ]() Concurrency applies to all simultaneous active voice calls across your entire organization, not to a single agent . How to Prevent Shutdowns 1. **Increase CPS Limits**: You can configure higher CPS limits per provider through your dashboard [(1) ]() . Start low and increase based on actual needs . 2. **Implement Retry Logic**: Use exponential backoff to handle throttling gracefully :

javascript
// Example retry logic
const maxRetries = 3;
let retryDelay = 1000; // Start with 1 second
for (let i = 0; i < maxRetries; i++) {
 try {
 await makeCall() ;
 break;
 } catch (error) {
 if (error.code === 'rate_limited') {
 await sleep(retryDelay) ;
 retryDelay *= 2; // Exponential backoff
 }
 }
}

3. **Upgrade Your Plan**: To increase CPS limits beyond defaults, you'll need to upgrade your plan [(2) ]() . 4. **Monitor Provider Limits**: Your telephony provider may have additional restrictions beyond Retell's limits [(1) ]() .

​ To learn more, see the sources I considered: [[1] Outbound Calls (Make Calls)](https://docs.retellai.com/deploy/outbound-call) [[2] concurrency calls](https://discord.com/channels/1186424376300679209/1460538188576592017) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.