(1) Short for communications over Internet Protocol CoIP is an extension of VoIP that refers to a set of standards used to define transmission of multimedia, including text, videos and images, over the Internet.
(2) Short for conferencing over Internet Protocol is used when two or more locations want to collaborate and interact using two-way video and audio transmissions simultaneously, over the Internet.  Also called collaboration over Internet Protocol.

VoIP? no, CoIP
Yarlagadda explains the concept of CoIP, which stands for Communications over IP (Internet Protocol).

Webopedia's "Did You Know...?" Section
Use this Webopedia knowledge section for an in-depth overview of specific technologies and occurrences in the areas of Computer Science, The Internet, and Computer Hardware and Software.