When Using iMessage on an iPhone, Is It Unlimited or Does It Run on Data?

Introduced in 2011, iMessage is a text messaging service that enables users to bypass traditional Short Messaging Service plans and communicate with any iMessage-enabled device without fees or restriction. IMessage has become a staple of Apple products and is one of the selling points of the iPhone. However, the service has left many iPhone users wondering how limitless and restriction-free iMessage really is and how -- if at all -- it affects their data plans.

IMessage is Apple's Internet-based text messaging service. IMessage works by using a new or existing Apple ID as a unique user name on a compatible device -- an iPhone, iPod Touch, iPad or Mac computer. This setup then enables the user to send and receive text, pictures or video messages using the Messages app and an Internet connection rather than a traditional cell tower network connection. IPhone users have the option of sending and receiving messages as traditional SMS or in the iMessage format within the iPhone settings. The easiest way to discern whether a message is an iMessage or a traditional text message is by the color of the conversation bubble. Conversation bubbles are green for traditional text messages and blue when iMessage is being used.

While Apple does not put a limit on iMessage usage, the service's need for an Internet connection causes certain restrictions. IMessage can and will use an iPhone user's data plan allotments to function if there is no Wi-Fi connectivity available and the user has allowed iMessage to remain active. Therefore, while Apple provides users unlimited access and usage of iMessage, the service can technically have usage limits based on the limitations set by any given broadband or data network provider.

IMessage runs through an Internet connection, but it is not likely to be the culprit of data overages incurred on an iPhone. A simple text message sent through iMessage uses a minuscule amount of data. An iPhone user with a low-end data rate plan could potentially send and receive many basic messages without causing any detrimental effects. Sending and receiving picture or video messages using iMessage uses more data, and if there is no Wi-Fi network available, this could potentially cause significant data usage depending the size of the photos and videos being sent and received. However, even this type of usage would have to be excessive to cause any noticeable data usage trends.

While iMessage does not use an egregious amount of data, there are still some precautions to take while using the service. If an iPhone user turns on the "Send as SMS" setting on the device, iMessages will default to using traditional SMS when no Wi-Fi or data network is available or in the event the iMessage servers are down. This could potentially cause unwanted usage charges for an iPhone user who incurs fees for receiving and sending standard SMS. In addition, when traveling internationally, roaming rates for even the smallest data usage can be expensive. The best practice when roaming is to disable all data traffic and roaming on your iPhone and use the iMessage service only while connected to Wi-Fi.