Good comments Steve. I'd say that they worst scenario I was in where I really had to muddle through was to support an antiquated phone system. It was a proprietary system that had limited connectivity and administrative options and it worked alongside a different proprietary voice mail system that was equally barren of documentation and support. Both systems were from different manufacturers who were no longer in business. No one at the plant knew much about them other than some very basic tasks, therefore it fell to me to figure out how to go beyond the basic tasks and perform true management including expansion and preventative maintenance. I was able to consolidate the management of them into a single dedicated PC connecting to them both via serial ports. Of course, no one was happier than I when the system was replaced with one much easier to manage and maintain.
I did learn an awful lot from that experience. While I've never had the need to manage another phone system since (and do not plan to do so again!), I did learn a lot about how to address problems, research issues, determine solutions and even to how to make improvements in a less than ideal situation.
...when ye are in the service of your fellow beings ye are only in the service of your God. -- Mosiah 2:17