Skype, MSN, Yahoo messenger

SKYPE

May be use in some ways. In phone calls, messages, and also videos are allowed in this service. Calls to other users within a skype are free. Wherever you are in the world, skype can bring you good services. You can download whatever you want.  Skype need internet connection so that you can enjoy using the services. Skype has several competitors, but has had huge success with home users due to its reliability, ease-of-use, and great marketing. Skype one concern is that they can act as a server for other people's calls, passing their voice data through your computer to its destination. Others have security concerns. Privacy is well taken care of as all calls are encrypted, but Skype is a popular attention application and is sure to attract hackers'.  Specifically it's free to use for text chat, and voice calls between any two Skype users on a Skype enabled devices. It's free to text chat with anyone on the Skype network anywhere in the world. Group text chat is also free. Some cell phones are able to run a Skype application that will allow you to use Skype whenever you are in range of an accessible wireless internet connection. 

MSN (WINDOWS LIVE MESSENGER)

Is an instant messaging client created by Microsoft that is currently designed to work with Windows XP (up to Wave 3), Windows Vista, Windows 7, Windows Mobile, Windows Phone, Windows CE, Xbox 360, Blackberry OS, iOS, Java ME, S60 on Symbian OS 9.x, and Zune HD.

It is the world’s largest easy to use consumer instant messaging (IM) service that allows people to connect with others in real time, expressing themselves in a rich, convenient and fun way. The name is new, but users will still be able to enjoy features they love, such as their contact list and emoticons, plus they will be able to experience all the new things that Windows Live Messenger has to offer.

Yahoo Messenger

Also known as YM, consider as the most convenient in terms of chat, videos, and downloads. Yahoo! Messenger is provided free of charge and can be downloaded and used with a generic "Yahoo! ID" which also allows access to other Yahoo! services, such as Yahoo! Mail, where users can be automatically notified when they receive new email. Yahoo! also offers PC-PC, PC-Phone and Phone-to-PC service, file transfers, webcam hosting, text messaging service, and chat rooms in various categories.