Look by the bathrooms.

There's a little space carved out of the convenience store to house the bathrooms; you suppose there could be a phone nestled back there as well, so you go to check it out. A large brown rat darts over your shoes as you turn the corner to see two battered doors, each depicting a stick-person, one of which wears a dress. Between the two is exactly what you needed: a filty, ancient, and probably unworking pay phone. Now all you need is money for the phone...oh, you don't have any? Well...