I am very new to the cs-cart software and what I am supposed to do is create a new settings option for supported phone numbers. So, to be more precise, as shown in the image below, I want to add a new option to the drop-down for an Indian phone number.

Also, I want to add functionality for this setting so that every field with the type "P" should only allow the format defined in the above dropdown. Furthermore, the number entered by the user should be prefixed with the +91 telephone code.