Whether you need to send a text message to Thailand because you have a friend there, you plan to partake in the country's tourism industry or you want to do business there, you must make a decision as to how you choose to do so. On one hand, you could use Thailand's country code (66) and send a text message using your mobile phone. Using this option, however, would accrue whatever costs your service provider applies--if you can send international SMS messages in the first place. Alternatively, you can send free text messages online using your choice of websites.
Visit Free SMS to Mobile (see Resources) to send a free text message to Thailand online. Drop down the "Select Country" menu and choose Thailand. Enter the Thai phone number (without the "66" country code), type your message (limited to 197 characters) and click "Send."
Visit SMS Free4All to send free, unlimited text to Thailand online if your contact in Thailand uses any of the following mobile providers: Advanced Info Service PLC; Digital Phone Co. Ltd.; Total Access Communications Co.; or True Move Company Ltd. Point your browser to the second link listed under Resources and enter the six- or eight-digit mobile number (no "08" mobile code) in the box, making sure to select the mobile provider from the corresponding drop-down menu. Enter your text message, the correct "CAPTCA" verification string and then click the "Submit" button.
Visit InternetSMS.com to send a free text message to Thailand. Select your country from the drop-down menu, then enter your e-mail address, the Thai phone number (no country code) and a message of up to 100 characters. Click the "Send" button.