Unlike Google Hangouts, Skype doesn't allow you to make non-international computer-to-phone calls for free. If you don't have a few bucks' worth of credit on your Skype account, add some before proceeding. Go to https://web.skype.com/. This will open your Skype page if you're already logged into Skype in your browser.  If you aren't logged in, enter your Skype email address or phone number, click Sign in, and enter your password to continue. As of September 2017, Skype web calling does not work with Firefox. You can use Skype web calling on Google Chrome, Internet Explorer, Microsoft Edge, and Safari. This grid of dots is on the left side of the page, just below your name and the "Search Skype" search bar. Type + followed by your country code. If you're calling your own phone in the United States, for example, you'd type +1 here. If you don't know your country code, click Choose country/region at the top of the page, then click your country's name. Type in the number for your own phone. It's the white receiver on a blue background that's in the upper-right side of the page. This green button is in the middle of the pop-up window. If you're using Microsoft Edge, skip ahead to the "Wait for your call to connect" step. Click the green Add Extension button, then click Add extension when prompted. This will install Skype Calling in your browser. It's a green button in the middle of the page. Clicking it prompts a setup file to download to your computer. Depending on your browser settings, you may have to confirm the download or select a location before the file will begin downloading. This will install the Skype plugin in your browser. This blue button is in the middle of the window. Doing so will proceed with your call. As long as you have enough credit on your account, your call will connect within a few seconds.

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Write a summary of the previous text in Vietnamese:
Bạn cần chắc chắn rằng mình có tín dụng Skype. Mở Skype phiên bản web. Nhấp vào biểu tượng trình quay số. Nhập mã vùng quốc gia. Nhập số điện thoại. Nhấp vào biểu tượng ống nghe điện thoại màu trắng nằm trên nền xanh ở phía trên bên phải trang. Nhấp vào Install Plugin (Cài đặt trình cắm) khi được nhắc. Cài đặt tiện ích mở rộng Skype. Nhấp vào Get Plugin (Nhận trình cắm). Nhấp đúp vào tập tin thiết lập. Nhấp vào nút Call màu xanh nằm giữa cửa sổ. Chờ cuộc gọi kết nối.