# Understand concurrency & limits

Understand the constraints and limitations of the agents.

We have enforced some constraints and limitations to ensure the smooth operation of your agents, and prevent any misuse of the service. Note that these constraints can be adjusted based on your operational needs, on a case-by-case basis.

### [​](https://docs.retellai.com/deploy/concurrency#concurrency)Concurrency <a href="#concurrency" id="concurrency"></a>

As part of our service, Pay-As-You-Go users are allocated a quota of **20 concurrent calls**. Should your operational needs require additional concurrency, you can go to “Billing” page to upgrade your plan.

![Billing Page](https://mintlify.s3.us-west-1.amazonaws.com/retellai/images/concurrency.png)

Billing Page

You can check your current number of concurrent calls in the dashboard.

* **Handling Multiple Calls per Agent**: You don’t need to create multiple agents to manage multiple calls concurrently. Each agent within your plan is capable of handling an unlimited number of calls, provided that the total concurrency remains within your designated quota. This means you can efficiently manage your workload without unnecessary agent duplication.

### [​](https://docs.retellai.com/deploy/concurrency#max-call-duration)Max Call Duration <a href="#max-call-duration" id="max-call-duration"></a>

The maximum duration of a call is **1 hours** by default, and the call will end automatically after 1 hour. Should your operational needs require longer calls, please reach out to our team at [support@retellai.com](mailto:support@retellai.com) to discuss options.

### [​](https://docs.retellai.com/deploy/concurrency#max-prompt-token-length)Max Prompt Token Length <a href="#max-prompt-token-length" id="max-prompt-token-length"></a>

The maximum length of prompt when using Retell LLM framework is **8192** by default, and longer prompt will be rejected when creating or updating the LLM. Should your operational needs require longer context, please reach out to our team at [support@retellai.com](mailto:support@retellai.com) to discuss options.
