Gmail’s chat now come with a new feature: SMS Text Messaging.
SMS Text Messaging in Gmail chat allows you to chat to your friend who is away from his or her computer. It will send the message via SMS to your friend’s mobile phone. In reply, your friend can simply reply to the number which he or her receives the SMS message. SMS messages from the same person will alway have the same number, so you can bookmark it as your friend’s “Online mobile SMS number”.
The feature currently only available to US number only. Also keep in mind, the text messages sent to Gmail count as part of your regular mobile messaging plan and might incur fees. Unless you or your friend has unlimitted text messaging plan, it will cost you a lot just for chatting using text messages.