[Q] SMS on hangouts not working topic

Guys tried sms from hangout but when I go to settings in the hangouts app.
It doesn't show me the SMS option whereas I can see the SMS option in
My mobile motog2 which also has the same lollipop versionas of my n9
Now what?
I'm using hangout version 2.5.83281670
I'm using the n9 lte version
Somebody please help