Sending an SMS text message to a cell phone using the computer is possible using a free SMS message provider. Many websites exist that provide the free service of sending SMS messages to cell phones all over North America and the world. Some sites allow the recipient to SMS you back, others do not. More sophisticated software allows the user to send MMS (multimedia) messages as well, but these services are not free.
Visit an online SMS messaging provider's site. There are a variety to choose from including txtDrop, txt4free and service providers like AT&T, Sprint and Verizon. Most phone service providers offer a free SMS messaging service on their website. All online SMS providers follow more or less the exact same format for submitting SMS messages.
Enter the "Phone Number" of the recipient. Enter your "Email Address" or "Cell Phone Number" (this is not required by all sites). Enter your message in the "Message" box. Try to keep the message short (under 150 characters) as some service providers will not deliver longer messages. Review the information.
Click "Send." The SMS message will be sent. Depending on the service the message was sent through, the user may be able to message back via e-mail or SMS. The message should be instantly delivered.