To add an alternate phone number to a customer profile via the manager side, navigate to Manager > Customer.
Search for the customer you wish to edit > Click on their name > Click on Cust Details.
On the customer profile; click on the "Alternate Phone" button.
Enter in the new number at the bottom of the popup then click "Add New".
The new alternate phone number will display in the list. You can indicate if the number is a mobile device by clicking on the "Mobile" checkbox.
If you need to delete the number, select the checkbox next to it then click "Delete".
Be sure to save your changes on the customer profile.