FlowerCo uses extensions which start with an 8 (well, technically they have 3 digit extensions internally and use 8 as a prefix on incoming calls). Switching them over to an NBX will be easy, except for the fact that by default, 8 prefixes are for the 8 pool, and extensions start at 1000.
Open up your dialplan and delete any TableEntrys which reference your 8 pool route, then update your ExtensionRange to include 8000 series extensions. If you want to maintain the functionality of the 8 pool, you can change it to use a 7 as the prefix by deleting references to the Diagnostics route in your initial tables, and replacing that TableEntry to be Local pointing to your 8 route
ExtensionRange Telephone 8000 8099 TableEntry Create 1 30 8 4 4 Internal 0 8 TableEntry Create 1 10 7 8 8 Local 0 1
Don’t forget to update your auto-discover settings to start assigning phones at 8000 (System-Wide Settings -> Enable Features System-Wide). If you want to remove the 8 pool entirely, just remove any of its entries in Table 1 and Table 2 of your dialplan.