Send-time optimization

EARLY ACCESS

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Use send-time optimization (STO) to send a message at the time an end user is most likely to engage with it  
STO uses historical engagement data for each end user (for example, message opens or URL clicks). Journeys and Broadcast use this data to choose a send time within the next 24 hours. To analyze the impact of STO on your journeys, see [Performance](https://www.infobip.com/docs/automation-studio/journeys/manage-journeys/performance).

STO cannot be used together with [frequency capping](https://www.infobip.com/docs/automation-studio/journeys/frequency-capping). If a journey is included in an active capping plan, it is not available for STO.

NOTE  
STO becomes available after you send your first 5 journeys. To use STO, you must enable [URL tracking](https://www.infobip.com/docs/messages/manage-messages#url-shortening-and-tracking).

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## Channels that support send-time optimization [#supported-channels]

STO is available for the following channels and engagement signals:

| Channel | STO options |
|---|---|
| SMS | Click rate |
| Email | Open rate, Click rate |
| Voice | Phone pickup rate |
| Push | Open rate |
| WhatsApp | Open rate, Click rate |
| Viber | Open rate |
| Telegram | Open rate |

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## Send-time optimization in journeys [#sto-in-journeys]

Send-time optimization enables the journey to choose the best time within the next 24 hours to send the message to the end user  
Enable STO in [Send elements](https://www.infobip.com/docs/automation-studio/journeys/journey-elements/channels#channel-elements) in your journey.

How STO works with a delivery time window:  
- Enable STO and configure a [delivery time window](https://www.infobip.com/docs/automation-studio/journeys/journey-elements/channels#delivery-time-window-channel-options) to restrict the send window.  
- Journeys try to find the best send time within the allowed window.  
- If no optimal time is found, the message is sent at the start of the window.

### Enable send-time optimization [#enable-sto-in-journey]

1. Select the channel element to open the side panel.
2. In **Tracking and reporting** > **Tracking options**, enable [Track URL clicks](https://www.infobip.com/docs/messages/manage-messages#url-shortening-and-tracking) (required for click-based optimization).
3. In **Message scheduling**, enable **Send-time optimization**.

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