My sister called me to earlier today to ask me a random question: is there a way for me to send SMS messages from my computer? Of course!, I told her. Here’s the reply I sent her, in case it’s useful to anyone else:
Approach 1: Sending SMS using Google Voice
- Go to http://voice.google.com/
 - Create yourself an account
 - Now from http://voice.google.com/ you can send and receive SMS messages.
 - The “from” phone number on these messages will be your Google Voice number.
 
Approach 2: Using Gmail’s chat feature to send SMS
- Google chat in Gmail has an SMS feature
 - On any contact in your chat list, you can choose “send SMS” (it’s there in the options)
 - It’ll ask you to enter a number for that person.
 - Now, from now on, if that’s person’s offline or online, you can send them SMS through google chat.
 - If they reply, it’ll show up in your google chat, archived in gmail.
 - Note: there are limits to how many SMS messages you can send before you get a reply… a safeguard against the service being abused by spammers