We have 2 fax lines for one building and need to be able to assign them to different departments.
We received hundreds of faxes and its easy for them to get lost in one big "pile". In our specific example, we have one that is scheduling/medical records and one that is business office. Business office is getting overwhelmed by going through all the medical records received and has missed a few of their assignments by it being "lost" in the weeds of the fax list.

At a minimum, the ability to filter the faxes by the numbers they were sent to and/or create a tag (similar to messages).
At minimum, I think the ability to filter the faxes to the incoming fax number is a must.