### Answer To restrict batch calls to specific time windows (8am-8pm UK time in your case) , you can configure the call time window when creating your batch call. [(1) ]() When creating a batch call, open the configuration modal to define the batch call time windows. You can set: - **Windows**: Define start and end times (e.g., 480 minutes from midnight = 8am, 1200 minutes = 8pm) [(2) ]() - **Timezone**: Set to your target timezone (e.g., "Europe/London" for UK) - **Days**: Specify which days calls should be made The

call_time_window

object in the API allows you to configure this:

json
{
  "call_time_window": {
    "windows": [
      {
        "start": 480,
        "end": 1200
      }
    ],
    "timezone": "Europe/London",
    "day": []
  }
}

For your 2000-number batch call, if it takes more than one day to complete, the system will respect these time windows across multiple days, only dialing during your specified 8am-8pm window. [(1) ]() **Note**: Currently, you cannot specify different time windows for different days of the week (e.g., weekdays only) - this feature is not yet supported. [(3) ]()

​ To learn more, see the sources I considered: [[1] Create Batch calls](https://docs.retellai.com/deploy/make-batch-call) [[2] Create Batch Call](https://docs.retellai.com/api-references/create-batch-call) [[3] Can I make the batch calls happen between certain times?](https://discord.com/channels/1186424376300679209/1359601275754512578) ​

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

### Answer The time window respects the timezone you specify in the

call_time_window

configuration, not Retell's server time. [(1) ]() [(2) ]() When you set the timezone to

"Europe/London"

, your 08:00-20:00 window will automatically respect British Summer Time (BST/UTC+1) during the summer months and Greenwich Mean Time (GMT/UTC+0) during winter months. [(1) ]() The

call_time_window

object uses the

timezone

field to determine when calls should run:

json
{
  "call_time_window": {
    "windows": [
      {
        "start": 480,
        "end": 1200
      }
    ],
    "timezone": "Europe/London",
    "day": []
  }
}

So when you configure your batch call with

timezone: "Europe/London"

and set your window to 08:00-20:00, Retell will respect the local UK time, including the BST offset when applicable. [(1) ]() [(2) ]()

​ To learn more, see the sources I considered: [[1] Create Batch Call](https://docs.retellai.com/api-references/create-batch-call) [[2] Create Batch calls](https://docs.retellai.com/deploy/make-batch-call) ​

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

### Answer Yes, you can configure the time window directly from the dashboard GUI. When creating a batch call in the dashboard, you'll see a step to "Configure the time window" where you can open the configuration modal to define the batch call time windows. [(1) ]() The dashboard interface allows you to set: - The specific hours when calls can run (your 08:00-20:00 window) - The days of the week - The timezone (which you should set to "Europe/London" to respect BST/GMT) This is part of the standard batch call creation workflow in the dashboard, accessible from the Batch Call tab where you clicked "Create Batch Call". The time window configuration happens before you choose to "Send Now" or "Schedule" your batch. The timezone you configure in the dashboard will automatically handle BST (UTC+1) and GMT (UTC+0) transitions throughout the year when set to "Europe/London".

​ To learn more, see the sources I considered: [[1] Create Batch calls](https://docs.retellai.com/deploy/make-batch-call) ​

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

### Answer Based on the documentation, the batch call time window configuration should include timezone settings. [(1) ]() [(2) ]() However, if you're not seeing the timezone option in the dashboard GUI at this may be a UI limitation or the feature may be available through the API only. The API documentation shows that

call_time_window

includes a

timezone

field: [(1) ]()

json
{
  "call_time_window": {
    "windows": [
      {
        "start": 480,
        "end": 1200
      }
    ],
    "timezone": "Europe/London",
    "day": []
  }
}

If the timezone field isn't visible in your dashboard interface, you have two options: 1. Use the API to create your batch call with the timezone explicitly set to

"Europe/London"

2. Check if there's a default timezone set at the account or agent level that the dashboard is using The documentation confirms that timezone configuration is supported for batch calls to ensure calls respect local time windows. [(1) ]() [(2) ]() If you're unable to set this in the dashboard, I recommend using the Create Batch Call API endpoint to ensure your UK time restrictions are properly enforced.

​ To learn more, see the sources I considered: [[1] Create Batch Call](https://docs.retellai.com/api-references/create-batch-call) [[2] Create Batch calls](https://docs.retellai.com/deploy/make-batch-call) ​

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

### Answer Retell AI's batch calling does support voicemail detection. When voicemail is detected, you can configure the system to either hang up or leave a message. [(1) ]() If you set it to hang up, calls that reach voicemail will have a disconnection reason of

voicemail_reached

. This means you can filter your batch call results by disconnection reason to identify which calls hit voicemail, then create a new batch call with just those numbers. You wouldn't need to manually track and reschedule them through your own system. To enable voicemail detection, navigate to your agent settings, open Call Settings, and enable Voicemail Detection. You can then choose whether to hang up or leave a message when voicemail is detected. The voicemail detection runs continuously within a timeout window (first 3 minutes of the call by default) . [(1) ]() [(2) ]() [(3) ]() When a voicemail is detected and you've configured it to hang up, the call disconnects immediately, even if the voicemail greeting is still playing. [(1) ]()

​ To learn more, see the sources I considered: [[1] Handle voicemail and IVR](https://docs.retellai.com/build/handle-voicemail) [[2] Get Voice Agent](https://docs.retellai.com/api-references/get-agent) [[3] Get Agent Versions](https://docs.retellai.com/api-references/get-agent-versions) ​

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