Sites represent the physical locations you’re migrating from CUCM to Teams. Define each site by name and country on the Sites tab, then choose which CUCM field identifies a site — Device Pool, Route Partition, Device Calling Search Space, or DN Calling Search Space — and map its discovered values to your sites on the Source Field & Mappings tab. Once mapped, every directory number is tagged with its site, populating the Site column in the CUCM Directory Numbers Report and driving the Sites by Migration Progress dashboard.