Related Links: FCC Narrowband Mandate Architectural Record Push-to-talk communication has been around since two-way radio came into use more than 70 years ago. Now, AT&T is putting a new spin on the sub-second communication feature with an enhanced push-to-talk service that can instantly reach up to 250 people simultaneously. It uses Internet Protocol as the conduit instead of radio frequencies.Steve Colkitt, IT director at CourierNet, which beta-tested the service, compares it to Motorola's pioneering iDEN (integrated digital enhanced network) service, which combined two-way radio capabilities with other features, such as pagers and fax/modem. "It's damn near iDEN quality, which no
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.