There are some things about the UI that could be improved that would help manageability on deployments with large numbers of extensions (in a single tenant).
1. Allow selectable page sizes. I am unsure where the 35 number came from but it would be better for this page size to be selectable. When trying to look through 3000 extensions, 35 is too small per page. It is also too small as the export extension option only exports the 35 exits displayed.
2. Allow extensions to be sorted based on the column headers. Again in large deployments, this helps make some things easier to find. Filters are helpful but sometimes do not capture the info you are after while a change in the sort would help much more.
3. Allow filtering by tags. Tags are nice to be able to set, except unless I go to the database and query manually, there is not much that I can do with them.
4. Expand what can be updated via mass update. After I import 100+ new extensions into TL for a new branch of a large company being added to the PBX, it would be nice to be able to be able to update the caller id fields (reg and emergency) on all of the extensions at once along with updating all of the tags associated with these extensions. Presently, I do this directly via MySQL as it is too tedious via the TL UI.