Group messaging on an iPhone occurs when you hold a conversation between two or more people using MMS, SMS and iMessage. On iPhones running iOS 8, hold group conversations using the native Messages app.
Setting Up a Group Message
To start a group message on an iPhone, open the Messages app and enter the name of the first person with whom you want to communicate. Enter a comma and type the name of the next person you want to add to the conversation. You can also add recipients directly from your contacts list by tapping the "+" icon to the right of the To field. Enter your message and tap "Send" to initiate the conversation. All the contacts you entered receive the same message. Subsequent responses appear together in the same Messages thread.
Adding Voice and Video
On iPhones running iOS 8, you can also add photos, voice and video clips to group messages. Tap and hold the "Microphone" icon to the right of the text input field to record your voice message. Tap the "Camera" icon to take a picture or video.
Leaving a Group Message
You can leave a group conversation at any time. If multiple parties are involved in the group message, the conversation continues, but you no longer receive messages. To leave a group conversation, tap the message thread in the Messages app. Tap "Details" in the top corner of the screen, scroll down and tap "Leave Conversation."