Start by creating a blueprint of how you would like to organize numbers. This means, understanding which operations, processes and configurations you'd want to build. For example: A delivery business has 100 numbers for Order Delivery in equal proportion in 4 regions - North, South, East and West. Their number organization structure would look like : Department - Delivery Business Operation - Order Delivery Processes and number configurations -
North (Configuration 1 - 25 numbers),
South ( Configuration 2 - 25 numbers),
East (Configuration 3- 25 numbers),
West (Configuration 4 - 25 numbers)
Organize numbers in the old console into number groups that resemble configurations of a process.
For example, creating a number group like "Sales - Bengaluru" in the older console can help in directly copying number group into a feature-set.
Post migration, your Call Me Back and User Feedback features will have to be enabled again. Hence, make sure to export the numbers used for 'Call Me Back' and 'User Feedback'. By doing this, you can easily set them up again in the new configuration once your numbers are moved there.
Once migration to the new console begins, managing numbers in the old one will become view-only. The sooner you complete migration, the faster you will regain new and upgraded controls in the new console.