The SIP (session initiation protocol) makes it possible for you to make VoIP phone calls to any phone number in the world using your existing internet connection. The SIP based phone calling feature is present in modern Android smartphones and iPhone, but the Windows desktop computers have no in-built system to make the SIP features available to the users. Fortunately the open source software MicroSIP allows you to make phone calls in Windows with any SIP account over the internet. It supports to the latest SIP standards and is available both as an installer and as a portable application.
Obviously, the first thing you have to do after launching MicroSIP is to add your SIP account. You can right-click on the MicroSIP system tray icon and select Account from the menu to open the Account settings.
In the Account Settings window, you can add the SIP account details like the SIP server, login ID, password, SIP proxy server etc. You can contact your SIP provider for all the setting details. If you do not have any SIP account, then you can get a free SIP account from callcentric or zadarma.
Once you have clicked on the Save button in the Account window, MicroSIP will login to the account and you would see a green Online status at the bottom of the MicroSIP window. This means that you are ready to make calls. If you have problem connecting, then try changing the transport protocol type to UDP (most SIP providers work very well on UDP). If your SIP provider has also assigned you a phone number, then you can also receive calls. In the same interface, you can increase or decrease the microphone or speakerphone volumes.
The MicroSIP window shows three sections dialer, calls and contacts. Under the Calls section, you will see all the calls that you have made or have tried to make. You can right-click on the calls and select Message to open the messages window which shows a log (messages received) when a call was made, e.g., the responses from the SIP server etc.
Although the default settings work perfectly for MicroSIP, you can modify the MicroSIP settings to suit your needs. You can open the settings from the system tray right-click menu. In the settings window, you can choose ringtone file (played when someone calls you), default speaker, microphone & camera devices, audio & video codecs, automatic answer settings and more.
Conclusion: MicroSIP is one of the best SIP clients for Windows. It is portable, uses very few system resources, supports not only the regular voice calls but also video calls and has encryption modules built-in. It is definitely a must have program for every modern Windows user.
You can download MicroSIP from http://www.microsip.org/.