When I joined the company, my employer had a microwave system covering most of our then footprint. It was fairly state of the art when it was installed, having 16 2-megabyte “tributaries” which could be used for either E1 30-channel telephone trunks between out PABXs or for 2MBPS data channels (2MBPS was then an acceptable data rate).
The system was costed over 5 years but because of some nifty routing techniques, putting all of our internal calls and data and even some external calls over the microwave, it paid for itself in 8 months in telco cost savings.
Around 10 years later, although the system was still working reliably, it could not support the considerable increase in data rates that we needed so we scrapped it. All our telephony and data was outsourced to telcos by bean-counter managers who didn’t have much understanding of how communications worked.