I have found info on sending with ios as seen here
http://forums.xamarin.com/discussion/4418/cant-pass-phonenumber-and-initial-text-for-sms-message-when-using-mfmessagecomposeviewcontroller
I have found info on sending with android using "intents" but i am unsure how to handle windows phone.
Ideally from inside the app i can launch the SMS window with the To: number and the Body: prefilled.
Help getting in the right direction
Thanks