Note: You might also see a message saying "Unable to sign in, please restart your device and try again"; this also might mean your software is out of date and you need to upgrade.
In this case, go to the App Store on your iPhone, search for Skype, and proceed from Step 2 below.
- Tap the Get it now button. This will launch the app store, and you'll be taken to the latest available version of Skype for your device and iOS version. Note that you will need a device running at least iOS 8 (iPhone 4s and above; iPad 2 and above) to run the latest version of Skype.
- In the App Store, tap the Update button.
Note: If your phone is running iOS 5 to iOS 7, you'll see the message below; tap Dowload to download the latest compatible version of Skype. For iOS 7 users, this is Skype 6.13 and for iOS 5 or 6 users, this version is Skype 4.17.
- Tap the Install button.
- Enter the password for your iTunes account, then tap OK.
- When the download completes, tap Open to open Skype.
- Select the type of account you want to sign in with (Skype Name is the most common).
- Then, simply use your Skype Name or Microsoft account to sign in to Skype.