Evaluation of Cellular Push-to-Talk Technology for First Responder Communications
This report presents the initial evaluation of cellular push-to-talk technology and its
functionality for enhancing two-way communications for first responders. Cellular pushto-
talk (PTT) is a new class of mobile telephony service that enables instant one-to-one
and one-to-many half-duplex communications on cellular phones making them work like
two-way push-to-talk radios. This report provides a brief overview of push-to-talk
systems and service factors of prime concern to public safety users. It presents a detailed
discussion of the testing and performance evaluation of three PTT systems with
nationwide coverage: Nextel's Direct Connect, Verizon Wireless' Push-to-Talk, and
Sprint's Ready Link. The performance evaluation served to identify that PTT is a
valuable technology for public safety users who can benefit from easy, instant access to
other users nationwide. All three services could stand performance improvement. Key
areas of improvement include:
- Use compatible technologies among different providers to enable users on
different networks to communicate.
- Reduce call setup latency on Verizon and Sprint networks.
- Provide priority access during network congestion (currently, only Nextel offers
first responders special features, available only for public safety users).
- Adopt roaming agreements among carriers to expand coverage areas.
The report presents the outcome of open discussions with officials from the Loudoun
County Fire Department about possible applications of cellular Push-to-talk systems. The
following include the most important suggestions:
- For large counties that are fully covered by radio systems, PTT can provide backup
communications to their primary radio systems, extending the range of
coverage geographically and/or enabling interoperability between agencies.
- Small counties in rural areas with small budgets to cover the high cost of building
a private radio system could benefit from commercial push-to-talk technology and
infrastructure in their primary operations.
- Other uses include emergent volunteers or certified teams to help during
incidents. The emergent volunteers can use commercial PTT service for
communications among other volunteer groups who have undergone disaster
training sessions that include use of PTT.
The evaluation of PTT solutions will continue as they evolve with the emergence of an
open Push-to-talk over Cellular (PoC) standard that will make cellular PTT services work
across carrier networks and operate on a variety of handsets and user devices. Building
on the PoC standard, next generation of PTT systems will be integrated with presence
and availability information of individuals and talkgroup members, offering expanded
communication options for public safety users.
