To enable the phone function, you must add a payment method under "Company Billing" in the settings and charge a minimum of $10 credit in order to send SMS/MMS.
Add Payment Method
Check your email for the direct link OR Go to "Setting" and click "Company Billing"
See your email
Setting -> Company Billing
Fill out your card information and click "Add Card"
After adding your card, you will be able to access the billing dashboard. Please note that a $1 refund will be processed to verify the validity of your card. This is not a charge, but you may see it as a pending transaction on your card which will disappear after a few days.
To view the full company billing transactions, you can click on 'See Details' under the Credit section.