Skype is a software application that allows users to make voice and live calls and chat over over the Internet. Skype supports conference calls up to 25 people at a time. Skype also supports video chat, including screen sharing, between two people for free. Group video calling is available for Premium subscribers between a maximum of 10 people.Skype does not provide the ability to call emergency numbers.Users may have more than one account; it is not possible to count users, only accounts.The volume of international traffic routed via Skype is significant. It has become the largest international voice carrier (by minutes of calls).
SMS Short message (or messaging) service, a system that enables cellular phone users to send and receive text messagesSMS is the most widely used data application in the world, with 3.6 billion active users, or 78% of all mobile phone subscribers. However, of late it's usage is dwindling due to the IM service
IM refers to Instant messaging .A web based service used for text-based communication between two or more participants over the Internet. IM allows effective and efficient communication, allowing immediate receipt of acknowledgment or reply. In many cases, instant messaging includes added features which can make it even more popular. For example, users may see each other via webcameras, or talk directly for free over the Internet using micro or headphone.
Email is a method of exchanging digital messages from an author to one or more recipients. Modern email operates across the internet and other networks of computers.The usefulness of email is being threatened by four phenomena: spamming,phishing, and email worms and viruses.
Voice mail system is designed to convey a phone caller's recorded audio message to a recipient.Most systems use phone-networks, either cellular or land-line based, as the conduit for all of these functions. Some systems may use multiple telecommunications methods, permitting recipients and callers to retrieve or leave messages through multiple methods such as PCs, PDA, Cellphones or Smartphones.
Chat refer to any kind of communication over the Internet, that offers a real-time direct transmission of text-based messages from sender to receiver, hence the delay for visual access to the sent message shall not hamper the flow of communications in any of the directions. Online chat may address point-to-point communications as well as multicast communications from one sender to many receivers and voice and video chat or may be a feature of a Web conferencing service