Now that nearly everyone carries a cell phone, the value of having these stationary phones is dubious. Still, some people think that having visible emergency phones throughout their facility is reassuring to customers and employees, so some clients are still are requesting them.
We use them in applications like corporate campuses, parking garages, and in surface parking lots. We usually locate them every 100' or so throughout the facility and link them to the video surveillance system so that the appropriate camera come up when someone activates an emergency phone. Some campuses also use them as part of their mass notification system so that every phone becomes a speaker when a campus-wide emergency message is broadcast.
Over the last couple of years, quite a few college campuses have determined that emergency phones are ineffective and have either removed them or have plans to do so. Studies have shown that the phones are rarely used and that any calls that are made are usually crank calls. Emphasis is now placed on making sure that students know how to call campus police with their cell phones in an emergency rather than providing emergency phones.
PRO's: Reliable (assuming proper maintenance), provides visible reassurance to employees and customers, works in places where cell phone might not (underground parking garages, etc.), can be used as a platform for other devices (cameras, mass notification, etc.)
CON's: High costs of initial installation and annual service, potential for abuse and vandalism, phones are not aways where needed (sometimes requiring users to travel in wrong direction to reach phone.)