Yah. There was a backdoor on all MS operating systems in net bios. As long as they were not behind a firewall and had not manually setup file sharing settings you could get full access / root.
All the way through the thousands there was a backdoor on OSX' remote desktop. As long as they were not behind a firewall and had not manually setup remote desktop, you could get full access as well.
And all the way through the 90s and the thousands, there was a backdoor on Motorola and Buffalo cable models, so you could remotely inject your own firmware and remotely reboot the router if you wanted. Everyone online was soldering those things to get hacked internet back then and I was just scratching my head as to why they were not using the backdoor instead.
I can go on. I haven't done anything infosec in a very long time. When I was 18 I got interested in certificate decryption and my passions took a more math heavy direction, eventually leading to quantitative finance.
edit: Oh, and to keep more on topic, regarding listening to cell phone chatter, the cell tower where I lived didn't change to digital until 2006, so in the thousands I knew you could listen in, but frankly I wasn't interested. I was more interested in making cantennas and injecting an 802.11 signal 2 miles away, decrypting their WPA. Surprisingly I did not find a single router that had a different admin password than its WPA password.
In the 90s all the way into the early thousands, to get online I had to get hacked internet, as my parents didn't really understand the internet and thought it was a fad. This may be what inspired some of the black hat stuff I did.
