@eric-cheng , Thanks for your reply. Here is the use case
1. Create a flow that will send a SMS using Twilio account
2. We define a Segment in Dynamics 365 Marketing
3. Create a Customer Journey
4. The Customer Journey sends an email based on certain conditions (OOTB)
5. The Customer Journey sends and SMS but there is no OOTB SMS
6. For SMS, we trigger the Power Automate Flow created in the first instance
7. There is no way to trigger that so, we create an Activity?
8. In Power Automate is there a way to trigger when an Activity is created?