2CO requires buyers to enter their orders and payment information themselves using the online interface.
This requirement does not restrict you to internet-based sales, however.
Accepting orders by telephone, facsimile or mail is acceptable as long as the payment portion of the process is done online. Please remember that vendors are not permitted to enter orders for their customers or accept credit card information as this contravenes the Credit Card Association rules that only a Merchant Account holder can collect credit card information.
You can easily send an email to customers containing the order details, along with a link, so the customer can enter their payment information.
For additional information on requesting a payment from the customer please review How Can I Send an Email to My Customer So They Can Make a Payment?