Skype is part of the culture at this point, with widespread use in both personal and public spheres. I'm often amazed at how many hot new "breakthrough" apps really just offer subsets of what Skype has offered for over a decade, apps like Kik, Oovoo, Viber, and WhatsApp. In our original review of Skype for Windows Phone (free, with optional service fees), our main beef was that it lacked background operation, making it pretty pointless for inbound communications. Microsoft, which bought Skype last year, has rectified that situation: The Skype app for Windows Phone now can accept and notify you about calls and chats no matter what else you're doing on the phone.

More than just for video-calling, Skype is pretty much an all-in-one communication service; not only does it offer voice, video, and text chatting with other Skype users, but you can call regular phones at much lower rates than you'd pay traditional phone carriers. Both subscription and pay-as-you-go credits are available, starting at $2.99 a month for US and Canada, and 2.3 cents per minute.

Setup and Signup
I installed and tested Skype for this review on a Nokia Lumia 928 running Windows Phone 8. You first agree to the full-page license agreement, which oddly states that the app might use cellular data even if Wi-Fi is available. Of course, if you already have a Skype account from desktop app use, you can simply sign in with that, and all your contacts and history will be replicated on the phone.

The next easiest option is to sign up for a Skype account using your Facebook account or Microsoft account (which you already have if you've used Hotmail, Outlook.com, or Messenger).

Absent any of those options, new users can sign up for a Skype account by entering an email, DOB, gender, language, mobile phone number, and a new Skype user name and password. After a CAPTCHA entry and email confirmation, you're ready for Skyping.

On first sign-in to a new account, the app asks whether you want to allow message notfications when the app is closed.

Interface
As you'd expect, the Skype app for Windows Phone sports the clean look formerly known as "Metro," with its large thin fonts and tiles.  The startup home interface lets you swipe through Favorites, Contacts, People (gleaned from the phone's People app), and Recent sections. On your profile page, you can set your status, either available or invisible, as well as enter a profile picture from the phone and a "mood message"—just a text status that shows up on your profile when contacts view it.

One annoyance for me is that theres' no search feature in contact list; you have to scroll down alphabetically to find who you want. Other than that, it's a highly clear and usable interface.

Voice and Video Calls
I can say with confidence that the voice quality of Skype, even on international calls, is actually better than cell service. Skype has long been in the forefront of developing codecs to make sure this is the case. Video call quality is more dependent on connection speed, and though at times it can look somewhat impressionistic, it's usually is good enough to make you feel you've really visited with your friend, relative, or colleague.

With broadband Wi-Fi connections on both sides, you can get surprisingly good "HD" video quality. Granted, it's not up to the quality of Apple's FaceTime, but that only operates within the restricted domain of Apple-only devices. You can still text while you're in a video call, but unlike Skype for desktop, there's no group video chatting.

IM Texting
Skype has for years let you send and receive instant messages as well as conducting voice and video calls. IM chatting in the Windows Phone app is more limited than on the desktop. You get the same set of smilies as in other Skype instances, and you can add more users for group chat. Earlier entries are time-stamped, but you don't see if your contact is typing, or if they read your message, as you can with most modern IM systems. IM clearly takes a back seat to voice and video.

Calling Cell Phones and Landlines
Many people are surprised when I mention that Skype lets you communicate with landlines and cell phones, as well as just with other Skype users, and the Windows Phone app supports all the functionality mentioned in this section. I frequently use Skype to call foreign numbers, usually just to get the other person to turn on Skype for a free voice or video call. You can reload your account in $10 increments, with calls costing from 2.3 cents a minute. You can auto-recharge this when your balance falls below $2. Alternatively, you can subscribe to unlimited service for $2.99 a month for U.S. (including Puerto Rico and Guam) and Canada; other plans, such as $1.19 a month for 60 minutes to China, or unlimited world for $13.99 a month.

You can also set up Skype to receive calls from plain-old phones and cellphones, with a Skype Number. This lets you receive actual calls in whatever Skype app you're running. Prices for this vary by country whether you have a subscription, but they start at a very reasonable $5 a month.

A couple caveats for using Skype to replace your phone: It doesn't offer local emergency calling such as 911 in the U.S. Also, sending SMS text messages is pricier than with most cell phones, at 11.2 cents per message. 

Missing Features
As is already probably pretty clear from the above, there are several Skype features found on other platforms that are missing in the Windows Phone app. I already mentioned the lack of video and voice messaging, which will no doubt appear in the app at some point. You also can't send photos or files, let alone share your screen.

As far as the competition goes, the newer Viber app and service has a couple advantages when it comes to call handling: It lets you move a call from your handset to your computer or mobile service easily, and lets you auto-answer calls with a text message. Skype is more of a one-device-at-a-time setup, though it's easy enough to see recent history on any of the devices and start another call. And remember that Viber doesn't do video—a Windows Phone version of Tango would be a better match, but that video-calling app is morphing into a gaming communication service, with support for new phones dwindling, including no more support for Windows Phone 8.

Skyping the Windows Phone Way
Despite lacking the features mentioned in the last section, Skype for Windows Phone contains everything you need for what most people want from the leading VoIP and video-calling service. Its ability to run in the background and display notifications for new messages and calls removes our biggest previous peeve. Skype earns a PCMag Editors' Choice not only because it offers excellent VoIP, IM, and video calling in a well-designed interface, but also because there's simply no other app or service that offers so much in the way of communication possibilities.