How can I view the Subaccount usage?

You can view all sent messages from within the subaccount itself at either SMS > SMS Overview or Voice > Messaging Overview.

Statistics for the subaccounts can be viewed from within the subaccount at Statistics > Overview. From the main account, all subaccount statistics can be found at Statistics > SMS > Subaccount texts.

Note: Message costs are only viewable via the main account and are not accessible via subaccounts.