SMS (Short Message Service) messages are text only. You can send a message up to 160 characters long. If you type more than that, your message will be sent in a series of SMS messages.
You can send one SMS to multiple people, and the replies will come in separate threads (unless you and your recipients have group messaging enabled).
SMS messages are included in most carriers' text messaging plans and don't use cellular data.
MMS (Multimedia Messaging Service) messages can include unlimited text and a photo, picture slideshow, video, or sound file.
You can send one MMS message to multiple people at once using group messaging, and replies will be delivered in group conversation threads to each person in the group.
MMS messages use cellular data, so you need a cellular data plan or pay-per-use payment to send them.
With group messaging, you can have a conversation with multiple people at once. All replies from recipients are delivered to all recipients, in a group conversation thread.
Even though you send one message to multiple people, you’ll be charged for each message received. Group messaging:
If you don't want to receive replies in group chats, you can turn off group messaging in the Messages app.
If you’re having messaging issues, try these troubleshooting steps.