What is the exact complete wording of the error message you are receiving?
What is the model number of your iPhone? Settings>General>About>Model.
You may have to scroll to see the entry for Model.
What does it say when you look at Settings>General>About>Carrier?
You may have to scroll to see the entry for Carrier.
If your wireless provider is charging you for the activation SMS, you are not
using a supported wireless provider. You may either change providers to avoid
these charges or work the matter out with your current provider, but FaceTime
and iMessage will not activate without that SMS being sent and responded to.
With which wireless provider in what country are you attempting to use
FaceTime and iMessage?