Skype
Must have

Skype

Windows/Linux/Mac OS
| home page | download |

Owner: Microsoft , reliable site.

iTunes
Android

Freeware

The main phone and instant messenger via the Internet.
Suffice it to say that Microsoft bought Skype for $80 billion. For that kind of money? Code Skype not worth it. Main - database. That's the main advantage of Skype is sitting there on Skype. You can install Skype, all find and to contact them.

The analogue of the toll NetMeeting