Try this:
- Handler initiated by client button press with active call selected (required in button press configuration)
- Mute Start Interaction1
- Place call to external number (I used an extended place call step) to create Interaction2
- Play digits
- Flush audio (if necessary)
- Mute Stop Interaction1
- Use Set Call State step to claim control of call (I set move to system queue, claim control, and cancel pending all to true)
- Use Transfer step to transfer Interaction1 to Interaction2