Emailing the text message to the SMS gateway of the service provider, using the MightyText app or the Messages app are three ways to send free text messages to mobile phones as of 2015. Whereas the Messages app is only available for Mac OS X, the other two methods work on all platforms.
Because service providers handle text messages through SMS gateways, it is possible to email a gateway to send text messages for free. Compose the text message as en email and send it to the recipient's phone number followed by the SMS gateway of their service providers. For instance, if the recipient is a Virgin Mobile customer, send the email to an address that looks like firstname.lastname@example.org.
Android users can use MightyText to send text messages for free. Unlike the SMS gateway method, MightyText can also handle MMS deliveries. MightyText is not a separate application and works on Internet browsers. It can sync the inbox on a computer and phone, and sends text messages through the phone number. As such, the recipient sees the message as if written from a phone even if a desktop PC is used to send it.
Alternatively, Apple users can send free text messages via the Messages application. The application comes as a part of the Mac OS X and iOS operating systems and can send messages directly to Apple computers and mobile devices. However, it cannot send messages to non-Apple devices.
If using the SMS gateway method, keep the message under 160 characters to avoid having the service provider treating the text as an MMS. Some service providers use separate gateways for MMS messages and the message may get lost.