Instant Messenger is no alien to Internet users. However most you may not be aware or not using its VoIP (Voice Over Internet protocol) services of your instant messenger.
In fact instant messenger service itself utilises a basic VoIP technology since most of them include VoIP.
Google is the latest participant in the area with their Google Talk. Here, you need a gmail account to make use of their services. At the time of this writing, gmail is still not offered to all. However Google is expected to offer it soon.
Using PC to Phone from messengers;
Once you install the messenger program, this is quiet straight forward. You would be just dialing directly from inside your program to any telephone (of-course PC to phone) is charged by all.
The reason people use it is due the cost advantage. However quality has not reached the level of an ordinary telephone communication yet. It could likely reach there in a few years. Convenience is great with many more features and utilities compared with the traditional phone calls.
Links to popular Messengers:
Google Talk Google is the latest entrance in the area with their Google talk!