Are there any 2nd line apps for Windows phone?

[digitaldd]

I know Google voice is out, and it appears the most popular ones for Android/iOS (line2/sideline/burner) do not seem to be available (even in copycat form i.e. where the app is not by the vendor offering the service but via a 3rd party). I know I can add a number by paying for it in Skype but do not want to have to always be logged into Skype to receive calls that way. I guess a dual sim phone would be an option too, though most of the time you lose SD card access with the second sim.

Any suggestions to add a second line to my Windows phone?