### Answer When using one agent for multiple customers with different voicemail requirements, each outbound call operates independently based on the parameters you provide at call creation time [(1) ]() . How it works: When you create an outbound call, you can override the agent's default voicemail message using the

voicemail_message

parameter in the call creation request . Each call maintains its own configuration—there's no "state" carried over from previous calls. Your specific scenario: - Call 1 (Customer A with custom message) : Uses the custom

voicemail_message

you specify in the API request for that call - Call 2 (Customer B with custom message) : Uses its own custom

voicemail_message

specified in that call's API request - Call 3 (Customer C using agent default) : Uses the

voicemail_message

defined in the agent configuration [(2) ]() —**not** the custom message from Call 2 The third call will receive the voicemail message defined in the agent configuration , not the custom message from the previous call. Each call is isolated and uses either: 1. The override value you provide when creating that specific call, or 2. The default value from the agent configuration if no override is provided This design ensures that one customer's custom voicemail message never "leaks" into another customer's call.

​ To learn more, see the sources I considered: [[1] Register Phone Call](https://docs.retellai.com/api-references/register-phone-call) [[2] Create Voice Agent](https://docs.retellai.com/api-references/create-agent) ​

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

### Answer Yes, exactly. The

voicemail_message

you provide when creating Call 1 and Call 2 is temporary and only applies to those specific calls—it's not saved to the agent configuration. [(1) ]() When you make an outbound call, you can use the

override_agent_id

parameter along with per-call overrides through the

agent_override

object. Any voicemail message you specify in the call creation request exists only for that individual call session. The agent itself has a persistent

voicemail_message

setting that serves as the default. [(2) ]() [(3) ]() [(4) ]() This default is what Call 3 would use if you don't provide a custom voicemail message for that specific call. Think of it this way: - **Agent configuration**: Permanent settings stored with the agent (including default

voicemail_message

) - **Per-call parameters**: Temporary overrides that apply only to that one call and disappear after the call ends Each outbound call is independent, and custom parameters you pass don't modify or persist in the agent configuration. [(1) ]()

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

​ To learn more, see the sources I considered: [[1] Outbound Calls (Make Calls)](https://docs.retellai.com/deploy/outbound-call) [[2] Handle voicemail and IVR](https://docs.retellai.com/build/handle-voicemail) [[3] Get Agent Versions](https://docs.retellai.com/api-references/get-agent-versions) [[4] List Voice Agents](https://docs.retellai.com/api-references/list-agents) ​