A system and associated apparatus and methods for providing enhanced security for transactions conducted over a network, such as eCommerce or a financial transaction conducted over the Internet. The system strengthens the security processes (e.g., user registration, authentication, and transaction acceptance or authorization) that are part of such a transaction to provide additional security for transactions conducted over a network (e.g., the Internet). The invention includes the use of a first communication channel or mode (e.g, the Internet) for entering user data and a second communication channel or mode (e.g., a response entered on a personal phone or VoIP connection) as a supplementary method of verifying the user's identity. The supplementary method may involve placing a call to a fixed line or mobile phone and requesting the user to confirm their identity by entering a alphanumeric string, speaking a password, executing a function on the device, or another similar action.