Creation of a sub account can be accomplished through the Account Settings box on your 2sms portal. By selecting the button, Sub Accounts, you will have access to create and modify sub accounts as well as maintain credit balances and address book access levels.
To create a new sub account, simply select the Open New Account button and fill in the required information. In creating the account, 10 credits will be removed from your master account to furnish your sub account with a starting balance. You are then able to add credits as needed to the sub account.