Downloadable software for use identifying or verifying the identity of participants in transactions conducted over local, wide area, or global computer and data storage networks; downloadable computer software for use in communications of alerts, reminders, notifications and marketing messages; downloadable computer software for use in set up, management, and use of two-factor authentication; downloadable computer software used to access databases to obtain information about phone numbers and to verify an end users device; downloadable computer software for use in identification of fraudulent phone numbers; downloadable computer software for use in management of receipt of SMS messages; computer software for use in shortening of uniform resource locators; downloadable computer software used for transmission of voice messages; downloadable computer software used for verification of user identity on computer networks used for peer-to-peer and social networking, instant messaging, and e-commerce transactions; Computer software for authentication, security, information sharing, messaging, and personal communications