Instant messaging requires the use of client software that connects to an instant messaging server. It differs from e-mail conversations in that it takes place instantaneously (almost in real time, time constraints are not strong in these systems). Most modern services offer a presence notification system, whether the individuals in the contact list are online.
Most instant messaging applications with Global Roaming Sim allow you to set a status message, which performs the same function as an answering machine message, for example to indicate the cause of an outage.
Instant messaging also integrate other features such as voice and video using a webcam, but also all kinds of collaborative applications (whiteboard, text editing, games), sending automated messages and notifications.
Instant messaging has its own language. The discussions taking place in real time, the write speed makes it more fluid, hence the use of writing shortcuts, especially to express the state of mind of the author (see emoticons). These shortcuts are often automatically replaced with a picture of smiley.
The multimedia messaging system (MMS) is a messaging standard that allows mobile phones to send and receive multimedia content, incorporating sound, video, photos or any other content available in the future.
Multimedia messaging with Global Roaming Sim allows sending such content to email accounts, expanding the possibilities of mobile communication, being able to publish your digital photographs or weblogs without the mediation of a computer. The file size limit of each multimedia message is usually 100 or 300 KB, depending on the phone, although this limit is defined by the operator or terminal characteristics and not the protocol.
The WAP Forum and Project collaborative third generation (3GP) define MMS to be an open standard. In principle, the MMS standard is independent of the type of transport and mobile network used and only defines a content synchronization system (SMIL) and encapsulation mode messages. Depending on the type of network, a method is used to alert the user device when there are new messages. Thus allows mobile users various networks multimedia messages can be sent without problems.
In GSM networks, GPRS is normally used for transmission in the radio interface, and warns the user device of incoming messages through a special SMS with a link to an Internet address where the message, called WAP Push message can be viewed. Many terminals automatically classify the incoming SMS as a multimedia message, and download content automatically and transparently to the user.
In addition, for the proper management of messages it is necessary to attach to the GSM network architecture a new message center number: the MMSC Multimedia Message Service Center, analogous to SMSC for SMS text messages).
