Even the first-generation Cisco Call Manager software I deployed 20 years ago had smart-support that differentiated between analog legacy-landline and digital/mobile callers, so we could deliver MOH audibly optimised to their individual listening-experience.
Back then my clients were mainly financial-institutions, and my licensed MOH was in lter years "Intro" by The XX -
https://youtu.be/NHMAx7AmK70
or earlier, "The Sun always Shines (on TV)" by A-Ha -
https://youtu.be/a3ir9HC9vYg
with the inevitable every-couple-of-minutes "We are a company licensed by the Financial Services Authority" interjection.