In order to use the Phone Companion, users had to sign in with a Microsoft Account, which would sync installation progress across devices.

[1] It was replaced by the Phone Link app in the October 2018 Update, but can still be accessed on prior versions.

On the Windows 10 Mobile screen, users are shown a list of apps that are already built-into their phone's system: Cortana, Photos, Groove, Movies & TV, OneNote, Skype, "Office" (Word, Excel, and PowerPoint only in this listing), and Outlook.

If the user selects the Android or the iOS screen, they will see a list of apps available for that mobile operating system, all of which support Microsoft account sign-ins: Cortana, OneDrive, Groove, OneNote, Skype, "Office", and Outlook.

[3] Microsoft does not list its cross-platform apps for Xbox, Solitaire Collection, Money, Sports, News, Weather, Sway, Delve, Office Lens, GroupMe, or Bing on the Phone Companion.