To send SMS alerts to Sprint cell phones using WebCam Monitor, you will need to configure your outgoing email server.
Click Tools >> Options >> Monitoring and click the configure button next to Email / SMS notification. Select the settings tab and choose 'Send email using outgoing mail server'. Fill in the details from your ISP mail server and the test email button should work. You may need to allow an exception in your firewall for WebCam Monitor to send email.