fix bug in retrieving phone number by sid

lib/routes/api/phone-numbers.js

@@ -79,7 +79,7 @@ router.get('/:sid', async(req, res) => {
     const account_sid = req.user.hasAccountAuth ? req.user.account_sid : null;
     const results = await PhoneNumber.retrieve(req.params.sid, account_sid);
     if (results.length === 0) return res.status(404).end();
-    return res.status(200).json(results);
+    return res.status(200).json(results[0]);
   }
   catch (err) {
     sysError(logger, res, err);