Good news! You can now send text messages to Globe, Smart or Sun cellular subscribers for FREE using Gmail Chat. You can send up to fifty text messages for free per day.
1. Log-in to your Gmail account.
2. Locate the Send SMS menu in the lower left portion of the page.
3. Enter the phone number, starting with the prefix "63" (example: 639171234567) then type your message and send.
Its that easy! And it is 100% working.
Visit this Google Help Page for more info.