If the sub-account is using your own Twilio account, you will need to reach out to Twilio support to get your toll free number registered.
If the sub-account is on LC phone, you can sign up for Toll-Free Number Registration for LC - Phone (US/Canada)
1. Head into your Location/ subaccount where you would like to purchase a Toll Free number:
2. Click on Settings at the bottom left:
3. Click on Phone Numbers
4. Click on Add Number
5. Click on the Country dropdown:
6. Select United States in the dropdown
7. Type "833"
Toll-free numbers are numbers that begin with one of the following three-digit codes: 800, 888, 877, 866, 855, 844 or 833. If it's not available for the one you are looking for, please reach out to support