Mobile IM and Presence

IM clients are also developed for mobile devices.

SMS's (short messages) may be considered a subset of Instant Messaging. Generally, an SMS may be stored by the carrier when the mobile device is not on. Additionally, the SMS will be stored on the device once it gets there and thus, not require the user to be actively interfacing with their phone.

Alternatively, IM clients will use the device's data service and generally require the recipient to have their device on. Because of this, a protocol has been developed to monitor an individual's Presence. For example, your IM contacts may determine whether the your phone is on or off, if you are in a call, if you are available, unavailable, or in a meeting. Additionally, they may be able to determine your location, your device's capabilities, even your current mood and a list of hobbies if you choose.