I would have posted this earlier, but I couldn't register on this site. I never got any emails.
Anywho... this is how you work it.
1. Find a Qwest/CenturyLink phone in Steamboat Springs, CO with an 870, 871, or 875 number.
2. Call 99X-XXXX (the last 5 digits of your number)
3. Flash hook at dial tone and hang up.
Heres a recording I made of it: