Who was he and what was his job title? Anybody know?

That was Jeff Bennett played by J. Alan Thomas. He was the dispatcher for the Sunshine Cab company.

Here's more info on Jeff, from ShareTV:

Who is Jeff Bennett?

Jeff Bennett (J. Alan Thomas) - Sunshine Cab's assistant dispatcher, he shares the "cage" with Louie but rarely speaks or interacts with the other characters. One exception is the Season 5 episode "Crime and Punishment", wherein Louie falsely accuses Jeff of stealing car parts from the company and selling them on the black market (a crime which Louie himself committed).