Based on a real phone booth that accepted incoming calls, isolated in the Mojave Desert, which gained an online following. Callers from many countries dialed (619) 733-9969, later (760) 733-9969, to see who would answer (often people who hiked to the spot). The phone was removed at the request of the Mojave National Preserve in 2000, and per SBC policy, the phone booth numbers were retired for good.
In the 1970s and before, all phone booths would take incoming calls. So people could wait for a call, or call back. Sometime in the 1980s, the phone company stopped this service, saying it helped drug dealers.