The IM2003 was the Entry Level - Builder Model and the was really the last of the original designs that can be traced back to the very first Music Intercoms that NuTone made in the 1950's.
It was the last model that would play music through the door speaker, the last model that had a "Push-to-Talk" button on the door speaker and the final modle to use an analog radio tuning pointer.
Even though the IM2003 was very dated by 1992, it was the most popular model sold in some parts of the country, especially Florida.