The phone number "is not registered with iMessage" Right now I can't seem to send some text messages from my OS X. Here is a list of things I have done that will have caused the error:


I fresh installed Yosemite about 2 days ago
I updated my iPhone to 8.1 this afternoon
I paired my device (I was able to send some texts from OS X)
I fresh installed iOS 8.1 on my iPhone
I can't send some text messages from my computer


When I start a new conversation on iMessage, the name of the person remains red. When I try to send a message I get a popup saying: " is not registered with iMessage". The handoff is well configured because I am able to see an icon appear in the dock when I use the notes app.

What can I do to make this functionality work again?

Thanks
You need to wait for the iOS 8.1 update in order to be able to do SMS from your computer / iPad. It should be available for you now or tomorrow if you go to "settings -> general -> software update"

EDIT: "iPhone Settings -> Messages -> Text Message Forwarding" then select your device that you want to send from and enable it :)

Restart messages on OSX if it's still not working.