[[kurono]]

Código Delphi [-]
uses
  FMX.Helpers.Android,
  Androidapi.JNI.GraphicsContentViewText,
  Androidapi.JNI.Net,
  Androidapi.JNI.JavaTypes,
  Androidapi.JNI.Telephony;

procedure SendSMS (target,messagestr:string);
var
  smsManager: JSmsManager;
  smsTo: JString;
begin
  smsManager:= TJSmsManager.JavaClass.getDefault;
  smsTo:= StringToJString(target);
  smsManager.sendTextMessage(smsTo, nil, StringToJString(messagestr), nil, nil);
end;

debes establecer permiso de envio de sms