In the early 1980s, “shoulder surfing” was practiced near public pay phones to steal calling card digits and make long distance calls. In those days, the wary traveler would cup his or her hand around the pay phone keypad so that others could not see the calling card number being keyed in.
How times have changed, as we are reminded by this nice airport amenity — a public telephone offering free calls to any telephone number in the US. What do you suppose it costs the airport to provide this amenity? Having had recent opportunities to learn about VOIP (voice over IP) and SIP (session initiation protocol) telephone service, I am delighted to be able to describe that it probably costs almost nothing for the airport (in this case, the otherwise rather inhospitable C-D concourse at Dulles) to provide this service.
A typical way to provide outgoing calls on a phone like this is to connect it to an ATA (analog telephone adapter) which in turn establishes a SIP trunk by means of an ethernet IP connection to a VOIP telephone service provider such as Voip.ms. It is easy to configure the trunk so that only US calls can be dialed, and it is easy to configure the trunk so that the call is only permitted to last five minutes.
A typical VOIP service provider charges no setup fee and no monthly fee for the SIP trunk. And the cost for the call is typically 0.9¢ per minute. So the five-minute call might cost the airport 4.5¢.
It’s a nice amenity, although during dozens of visits to this concourse I have never actually seen the phone in use. I suppose it is most helpful for the occasional passer-by whose mobile phone has run down its battery.
A tip of the hat to Dulles airport for this nice amenity.