When you create a call flow, you have to make sure you assign it to any (or all) of your phone numbers.
Setting this up is very easy.
1. Go to your "Settings", then "Phone Numbers"
2. Select the phone number you want to assign a new call flow to. Within the phone number profile, you will se an option for "Call Flow". From the dropdown list, select the call flow you want to assign.
3. When you're ready, click on "Save".
Please don't hesitate to contact Support if you need further assistance.