Everything You Need to Know About SMS & MMS on the iPhone

The terms SMS and MMS come up all the time when discussing text messaging, but you may not know what they mean. This article provides an overview of the two technologies, what they mean, and information about how they're used on the iPhone.

While this article is really designed to explain specifically how SMS and MMS are used on the iPhone, all phones use the same SMS and MMS technology. So, what you learn in this article applies generally to other cellphones and smartphones, too.

What is SMS?

SMS stands for Short Message Service, which is the formal name for the technology used for text messaging. It's a way to send short messages from one phone to another. These messages are usually sent over a cellular data network. (That's not always true, though. For instance, iMessages can be sent over Wi-Fi. More on that below.) 

Standard SMSes are limited to 160 characters per message, including spaces. The SMS standard was defined in the 1980s as part of the GSM (Global System for Mobile Communications) standards, which were the basis of cellphone networks for many years.

Every iPhone model can send SMS text messages. Early models of the iPhone used a built-in app called Text. That app was replaced by Messages, which is still used today.

The original Text app could only send standard text SMSes. That meant that it could not send images, video, or audio. The first-generation iPhone was criticized for lacking multimedia messaging because other phones already had that feature. Later iPhone models with different versions of the operating system gained the ability to send multimedia messages.

If you want to go really deep into the history and technology of SMS, Wikipedia's SMS article is a great resource.

The Apple Messages App & iMessage

Every iPhone, iPod touch, and iPad since iOS 5 has come pre-loaded with Messages, the app that replaced the original Text app. (The Mac got its version of Messages in macOS X Mountain Lion, version 10.8, in 2012.)

While the Messages app lets users send text and multimedia messages, it also includes a feature called iMessage. This is similar to, but not the same as, SMS:

• SMS messages are sent through phone company networks. iMessages are sent between through Apple's servers, bypassing phone companies.
• SMS messages are only sent over cellular networks. iMessages can be sent over cellular networks or Wi-Fi.
• SMS messages are not encrypted, while iMessages are protected with end-to-end encryption. This means that they can't be intercepted and read by third parties like phone companies, employers, or law enforcement agencies. For more on digital privacy and security, read Things To Do on Your iPhone to Stop Government Spying.

IMessages can only be sent from and to iOS devices and Macs. In the Messages app, iMessages are the blue word balloons. SMSes sent to and from non-Apple devices, such as Android phones, don't use iMessage and are shown using green word balloons.

IMessage was originally designed to allow iOS users to send each other SMSes without using their monthly allotment of text messages. Phone companies generally now offer unlimited text messages. Still, iMessage offers other features that SMS doesn't, like encryption, read-receipts, deleting individual texts and full conversations, and apps and stickers. 

What is MMS?

MMS, aka multimedia messaging service, allows cellphone and smartphone users to send each other messages with images, videos, and more. The service is based on SMS, but adds those features.

Standard MMS messages can support videos up to 40 seconds long, single images or slideshows, and audio clips. Using MMS, the iPhone can send audio files, ringtones, contact details, photos, videos, and other data to any other phone with a text messaging plan. Whether the recipient's phone can play those files depends on that phone's software and features.

Files sent via MMS count against both the sender's and the recipient's monthly data limits in their phone service plans.

MMS for the iPhone was announced in June 2009 as part of iOS 3. It debuted in the United States on Sept. 25, 2009. MMS had been available on the iPhone in other countries for months before that. AT&T, which was the only iPhone carrier in the U.S. at the time, delayed introducing the feature due to concerns over the load it would place on the company's data network.

Using MMS

There are many ways to send an MMS on the iPhone:

• In the Messages app the user can tap the camera icon next to the text-input area and either take a photo or video or select an existing one to send.
• Users can begin with the file they want to send and tap the sharing box. In apps that support sharing using Messages, the user can tap the Messages button. This sends the file to the iPhone's Messages app where it can be sent via MMS. 
• Apple Music supports sharing via MMS.