After an initial, limited release for its enhanced Push-to-Talk (PTT) service, AT&T has now expanded the program to businesses of all sizes.

According to AT&T, the average PTT conversation lasts less than 40 seconds, compared to 3 minutes for mobile calls, making the service ideal for businesses such as delivery or service fleets that need quick, instant access to communications.

AT&T launched this service to address customers served by the Sprint Nextel iDEN Network that is being disbanded. The new service is an IP-based solution which offers fast, sub-second performance and advanced features, the company said. It also allows for integration with back-end office systems and applications on a single platform, including the ability to work with PBX and WiFi networks.

PTT is designed for 4G LTE and includes a number of devices capable of handling the service, including the Samsung Rugby III, Samsung Galaxy Rugby Pro and the Sonim XP5560 Bolt.

The service also runs on both the BlackBerry Curve 9360 and BlackBerry Bold 9900. AT&T is offering several of these devices for free through AT&T Business Solutions with an AT&T Enhanced PTT two-year contract.

Among the features of PTT, AT&T said, are larger contact lists and talk groups than competitive PTT solutions, the ability to combine PTT services and mobile applications, access to AT&T’s 4G network, supervisory override and talk group scanning, and sub-seccond call setup.

Rate plans being offered include a $5/month charge when added to existing AT&T voice and data plans or a $30/month for a PTT-only rate plan (no voice or non-PTT data included). Both plans include unlimited PTT, and data used by the Enhanced PTT application will not count against the customer’s monthly data totals or incur pay-per-use charges, AT&T said.

“For workers in industries like construction, manufacturing and public safety, mobile devices that can withstand harsh conditions are essential. We’re offering AT&T Enhanced PTT on a variety of rugged devices to give our customers the performance and durability they need to get in touch quickly on the job – no matter what conditions they face,” said Chris Hill, senior vice president, Advanced Solutions, AT&T Business Solutions.