Email (electronic mail) is a means of transmitting computer-based messages over a network, typically the Internet. Today's email programs are often bundled with other tools designed to improve collaboration, such as calendars, contact lists, and task lists. 

A fax (short for facsimile) is a document sent over a telephone line.

File transfer is a managed method of transferring data from one computer to another. As an alternative to email, file transfer is sometimes necessary to address security, size, and/or automation.

Instant Messaging (IM) allows real-time communication with contacts. 

Unified communications (UC) is the integration of real-time communication services such as instant messaging, presence information, telephony, video conferencing, call control, and speech recognition with non-real-time communication services such as voice mail, e-mail, and fax.

Video communication enables face-to-face interaction in real time between two or more people using video and audio technologies.

Voice services include dial tone and telephone support as well as consulting, design, and engineering of voice technologies and applications.