Leg day at the office
Once, while working at a customer's premises, I got a call from a potential new employer. Not wanting to be overheard, I wandered into the service stairs for some privacy.
After ending the call, I tried to go back, but the doors only opened from the inside without a card, something I hadn't been provided with. I had my phone with me but, unluckily, no service in there.
I tried knocking on the door hoping someone would listen, but in the end I had to walk down 18 floors to the entrance lobby, then call my client so I could return as I hadn't brought any ID with me....