Update permanent failure error message description

app/templates/views/message-status.html

@@ -55,7 +55,7 @@
         ('Sending', 'Notify has sent the message to the provider. The provider will try to deliver the message to the recipient for up to 72 hours. Notify is waiting for delivery information.'),
         ('Sent internationally', 'The message was sent to an international number. The mobile networks in some countries do not provide any more delivery information.'),
         ('Delivered', 'The message was successfully delivered. Notify will not tell you if a user has opened or read a message.'),
-        ('Phone number does not exist', 'The provider could not deliver the message because the phone number was wrong. You should remove these phone numbers from your database. You’ll still be charged for text messages to numbers that do not exist.'),
+        ('Not delivered', 'The provider could not deliver the message. This can happen if the phone number was wrong or if the network operator rejects the message. You should check that these phone numbers are correct. If not, you should remove them from your database. You’ll still be charged for text messages that cannot be delivered.'),
         ('Phone not accepting messages right now', 'The provider could not deliver the message. This can happen when the recipient’s phone is off. You can try to send the message again. You’ll still be charged for text messages to phones that are not accepting messages.'),
         ('Technical failure', 'Your message was not sent because there was a problem between Notify and the provider. You’ll have to try sending your messages again. You will not be charged for text messages that are affected by a technical failure.'),
       ] %}