Sending group SMS from iPhone is easy. First download app called “group SMS” from app store.
After installing open the app and you will see the main page where you can see different options at the bottom likegroups , mail, message, keypad and settings.
Click on message and a new window opens asking you to select the people whom you want to send messages.
By default each contact is selected. Click compose to start messaging. You will go back to the selected group after you send the message