In addition to sending, messaging handles the exchange of messages and communications and the adaptation offile formats to the requirements of messaging clients. The reformatting of file formats is handled by the messaging server. Messaging includes electronic media and services such as the creation and transmission of text, images, voice, fax, e-mail, paging, chats, and the various messaging services such as Short Message Service( SMS), Instant Messaging( IM), Unified Messaging Service ( UMS), and others.
Depending on whether the messaging is between persons and/or applications, a distinction is made between person to person( P2P), application to person ( A2P), person to application( P2A) or application to application( A2A). Off-the-record messaging( OTR) is a secure variant with end-to-end encryption( E2EE) that prevents unauthorized parties from accessing the message content.