### Answer When publishing an updated prompt version, ensure you're only working with one prompt editor open at a time [(1) ]() . Having multiple editors open can cause your saved changes to revert to an older version . Key steps to verify: 1. Close all other prompt editor tabs - Make sure you only have one instance of the prompt editor open when saving changes 2. Check the version parameter - When updating via API, you can specify the

version

parameter to ensure you're updating the correct version [(2) ]() [(3) ]() 3. Verify the agent is using the updated LLM - If you're updating a Retell LLM, ensure your agent's

response_engine

points to the correct

llm_id

and

version

[(3) ]() For example, when updating an agent to use a specific LLM version:

json
{
  "response_engine": {
    "type": "retell-llm",
    "llm_id": "llm_234sdertfsdsfsdf",
    "version": 0
  }
}

Workaround for tracking changes: Since there's currently no revision history available [(1) ]() , consider manually copying and pasting your prompts into a version control system like GitHub to track changes . If the issue persists after ensuring only one editor is open, try creating a test call to verify which prompt version is actually being used in the call history.

​ To learn more, see the sources I considered: [[1] Saved prompts reverting to an older version](https://discord.com/channels/1186424376300679209/1342602227650396160) [[2] Update Retell LLM](https://docs.retellai.com/api-references/update-retell-llm) [[3] Update Voice Agent](https://docs.retellai.com/api-references/update-agent) ​

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

@AI Evy In "versions", what's the difference between the DRAFT and the PUBLISHED?

### Answer The key difference between DRAFT and PUBLISHED versions: DRAFT version: - This is your latest editable version [(1) ]() - You can modify and change the agent configuration - When you select "Draft" for a phone number, it will always fetch the latest version of the agent - Only the latest version can be changed PUBLISHED versions: - These are locked and cannot be changed [(1) ]() [(2) ]() - Published versions are fixed with specific version numbers (0, 1, 2, etc.) [(1) ]() - Once you click "Deployment" to publish, that agent version's configuration, system prompts, and behavior won't change [(2) ]() - Phone numbers bound to specific published versions will continue using that exact version number Important behavior: When you assign a phone number to a version, it doesn't auto-upgrade to your latest draft . If you set a phone number to use version 1, it stays on version 1 even if you later publish version 2 [(1) ]() . To use updated prompts in production, you need to either: 1. Publish a new version and update your phone number assignment to that version 2. Set the phone number to use "Draft" (which always uses the latest) This versioning system helps you lock in stable configurations for production while continuing to develop and test changes .

​ To learn more, see the sources I considered: [[1] Setup versioning for agents](https://docs.retellai.com/agent/version) [[2] Old system prompts are being used in production](https://discord.com/channels/1186424376300679209/1392838623023595600) ​

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

### Answer The "TEST" button uses your draft version, while your phone number is likely still assigned to an older published version [(1) ]() . To reassign your phone number to the updated version: 1. Via the Phone Numbers tab - Go to the "Phone Numbers" tab in your dashboard . Select your phone number and choose either "Draft" (to always use the latest version) or select the specific published version number you want [(1) ]() [(2) ]() . 2. Via the Publish modal - Click the "Deployment" button in the upper right corner of the agent page [(1) ]() . In the modal, you can attach phone numbers for production use . 3. Via the Version History - Click the Clock icon in the upper right corner to view all versions . Select the version you want, then click "Update Deployment" to attach phone numbers . Key point: If you select "Draft", it will always fetch the latest version of the agent . If you select a specific version number, the phone number will stay locked to that version even when you publish newer versions . Since you deleted the phone number assignment, use any of the three methods above to reassign it to your desired version.

​ To learn more, see the sources I considered: [[1] Setup versioning for agents](https://docs.retellai.com/agent/version) [[2] Discord message from @omar.13. on 2026-02-02](https://discord.com/channels/1186424376300679209/1186462578310910112/1468001724760326214) ​

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