diff --git a/lib/postgresql_interface.js b/lib/postgresql_interface.js
index a676281a..d80be7b9 100644
--- a/lib/postgresql_interface.js
+++ b/lib/postgresql_interface.js
@@ -489,16 +489,16 @@ function insertDispense (client, session, tx, cartridges, transactionId, cb) {
 
 exports.addIncomingPhone = function addIncomingPhone (session, tx, notified, cb) {
   var sql = 'UPDATE transactions SET phone=$1, notified=$2 ' +
-    'WHERE incoming=$3 AND device_fingerprint=$4 AND session_id=$5'
+    'WHERE incoming=$3 AND device_fingerprint=$4 AND session_id=$5 AND phone IS NULL'
 
   return new Promise((resolve, reject) => {
     connect(function (cerr, client, done) {
       if (cerr) return reject(cerr)
       var values = [tx.phone, notified, true, session.fingerprint, tx.sessionId]
-      query(client, sql, values, function (err) {
+      query(client, sql, values, function (err, results) {
         done(err)
         if (err) return reject(err)
-        resolve()
+        resolve({noPhone: results.rowCount === 0})
       })
     })
   })
diff --git a/lib/routes.js b/lib/routes.js
index f95217fb..5f752613 100644
--- a/lib/routes.js
+++ b/lib/routes.js
@@ -240,7 +240,7 @@ function phoneCode (req, res) {
 function updatePhone (req, res) {
   const notified = req.query.notified === 'true'
   return plugins.updatePhone(session(req), req.body, notified)
-  .then(code => res.json(200))
+  .then(res => res.json(res))
   .catch(err => {
     logger.error(err)
     res.sendStatus(500)