If you hear someone's walkie talkie say something like, "Toys, you have a call on 35" then you can run to a phone and dial 35 to talk to a customer. Lines can be picked up by dialing 35 or 36.
The electronics department in my Target has a cordless phone in their electronics department. It's the same Uniden model that I use in my kitchen. So I could bring my extra handset into Target and initialize it with their base station and I would have my own Target extension!
I really want to do this. To initialize the handset, I have to drop it into their base station for 5 seconds and it will automatically do its thing. I think I could do this while the electronics guy is away from the counter. Or is there a way I could social engineer them into doing it? Maybe say, "I bought this phone and it does the CRAZIEST thing when I drop it in the base. Just watch this!" If a dumb teen girl was working, she probably wouldn't be suspicious of that.
This is a 5.8 GHz phone which should get a range of 300 to 2000 feet. I'm not sure if I could take it outside the store, but even if I was stuck inside the store I could just walk around taking calls for the store and I doubt I'd be noticed. I bet if I didn't abuse it nonstop, it would last forever. Or until they upgrade their cordless phone at least.