You can add users to your account and specify their role, which will dictate their permissions. To do this, you can expand the settings menu by clicking "Settings" from the column on the left of the online portal.
From this menu, select "Users" to bring you to the users menu.
On this page you will see your existing users and their assigned roles.
To add a new user, click the "Invite User" button on the upper right of the page. This will open a window where you can enter an email and choose what roles to assign to them. The "Admin" designation will permit the user to access and alter anything. The "User" designation allows the user to access and alter everything but the billing portion of the account (invoices, update the payment information and view minute totals). The "Billing" designation will only allow the user to access invoices, update the payment information and view minute totals. The "Reporting" designation only permits the user to access Call Analytics.
When you are ready, click the "Invite" button on the bottom right of the window.
If you have multiple numbers, another prompt will open which allows you to specify which numbers the user has access to.