Must Be One Of The Older Numbers

I worked at Blackberry tech support. After activating a customer’s phone:

Me: “Okay, now you need to dial a number and hit ‘send’ to see if you can make a call.”

The call failed. We did some troubleshooting but to no avail. After half an hour of him dialing a number and getting “call failed”:

Me: “Hmm… maybe it’s a problem with who you’re calling. What number are you dialing?”

Customer: “Twelve.”