Cannot Add Phone Number to SMS Notifications in User Profiles

Steps to reproduce:

Go to the /server_admin/notifications
Enter Test Account SID and Test AuthToken, e.g. AC7d9d7892ddba3605d047e753632fb437 and 98509000549a29acfa04c39e678559df
Enter a phone number created for that twilio account, e.g. (919) 555-1212
Click Save

All fields are then blanked out (see HCPUB-854) but a "Success" message is displayed.

Next, as a user, navigate to your profile and click "Edit Profile"
Click Notifications
Click "Add Phone" beside "SMS"
Enter phone number (e.g. (919) 555-1616) and click "Send Confirmation Code"

Expected result

User will get a confirmation code sent via SMS

Actual result

Trying to add the phone number on the '/account/mobile' will result in a message 'We were unable to send your confirmation code to '(919) 555-1616'. Please make sure the number is valid.' is shown. It doesn't matter what format the phone number is entered in (e.g. 9195551616 919-555-1616). The user will get a rejection error.

It was verified that this functionality still works fine on HipChat Server 1.3.9.