This is what happened when i tried it. I asked the girl to transfer me to extension 7 which she did. I heard ringing as if it was transferring me there but then she picked up again and said that it was asking her for a zone code, to which i responded 80. Then she said is was asking her to record a message. So it sounds like it does work, but they were the ones hearing the prompts. I'll try some other stores and if i find anything interesting i'll post it.
EDIT:
I called a second store and the same thing happened. Only they heard the prompts, it was all on their side.