Here is how you e.g. inform your customers that appointments for tomorrow are cancelled:
1. Install this app to your Android phone
2. Install GroupMessaging client on your PC or Mac (http://ovrlasit.wordpress.com/group-sms/)
3. Start both of the applications
4. Select recipients from your contacts on the PC or paste the list in
5. Write & send the group sms message from the PC via your phone
Update 2014-05-31 Fixed links to instructions & client JAR.