Search for the service with the DID phone number you want to edit the route plan for in one of these ways:
Sort your services using the Sort by… list (e.g., Service Type). You can toggle between descending and ascending order using the arrow to the right of the Sort by… list.
Filter your services by selecting an option from the View All (Default) list.
Search for the service (by service type, account, etc.) using the Search by… field and search box. (To search using multiple search criteria, click Advanced Search, then fill in your search criteria and click Apply Search Filters. When you're done, click Close Advanced Search.)
When you find the service, click the green arrow on the right of the line for the service, then click the DID Telephone Number Management section.