Step 1:
The first thing is to restart the All services go to your management console > System Status > Services and Restart All.
Step 2:
After the services Restart you will need to go to Extensions select all and go to edit.
Step 3:
Click ok.
Now you can send a new welcome email to the users and re configure the phone .
Step 5:
Instruct End Users to Open email attachment to re-provision app