Regent Sign Company. ALgonquin 4-9116.
Bugs like this for the Regent Sign Company and other signage makers are among the most commonly seen Telephone Exchange Name Sightings. They are tucked in the corners of larger signs.

ALgonquin Telephone Exchange Sighting. Emil Talamini Real Estate.
Emil Talamini Real Estate used to be at 450 Sixth Avenue. Their phone number was ALgonquin 4-1817.