Introduction to Push-to-Talk

Introduction to Push-to-Talk

Push-to-Talk (PTT or P2T), originally introduced in the US by Nextel through its partnership with Motorola and its use of the iDEN technology is now poised to emerge as one of the premier voice-based VAS applications for many leading mobile communications service providers. Combining aspects of cellular mobile communications, presence detection, and walkie-talkie style communications, push to talk provides end-users with the ability to quickly find one another and engage in brief, burst-oriented style communication. Advances in market adoption and technology evolution of voice over wireless IP will enable improvements in Push-to-Talk (PTT).

Push to Talk over Cellular (PoC) introduces a new real-time direct one-to-one and one-to-many voice communication service in the cellular network. The principle of communication behind the service is simple - just push to talk. Thanks to the 'always-on'1) connection, calls can be started to both individuals and talk groups with just a push of a key. The call connection is almost instantaneous and the receiver doesn't have to answer the call.

Push to Talk service users are typically engaged in some other activity than a telephone call, and they listen to the group traffic during their activity. A user can be contacted by the name, or he may occasionally want to say something to the group. Half-duplex traffic is ideal for such use cases. This simple, real-time direct communication serves the diverse needs of both business users and private consumers ranging from controlled team management to spontaneous sharing of experiences. Among the many benefits of this solution over conventional two-way radio systems are the attractive cellular phones and the simple and fast creation of talk groups and group calls.

Push to Talk service is a genuine differentiated voice service, because it is not a substitute of any existing cellular services. It gives operators an opportunity to develop their voice service offering without changing conventional voice services.

The Push to Talk service is an integral part of the IP Multimedia communication portfolio envisioned by Nokia, and a part of the service offering in IP Multimedia Subsystem (IMS). It is based on half-duplex Voice over IP (VoIP) technology over mobile networks. Thanks to the IP technology, the Push to Talk service uses cellular access and radio resources more efficiently than circuit-switched cellular services, reserving network resources only for the duration of talk spurts instead of for an entire call session.

Nokia believes that Push to Talk service must be based on open standards to enable multivendor environment and interoperability between different terminals and services. Nokia has been the main contributor for the coming OMA (Open Mobile Alliance) PoC standard, which is now under IOP (Interoperability) testing. This solution offers terminal manufacturers an opportunity to implement the Push to Talk facility across mobile phone categories, thus giving end-users more freedom to choose the products that best meet their communication needs.