Overview
Typically, a mobile telecommunication network is classified either as a Public Access Mobile Radio (PAMR) network or a Private Mobile Radio (PMR) network. The private communication system, also called the trunking system, fulfills the requirements of departments, industries and companies in production dispatch, and public security and safety applications. 

At the early phase of trunking communications, a fleet such as a department or company, usually builds a professional system for its dedicated use, which is called the Private Mobile Radio (PMR) system. 

The Public Access Mobile Radio (PAMR) network is normally run by a network operator and can support tens to hundreds of thousands of users within an area. Different from the PMR network used by a fleet, the PAMR network offers services to a number of fleets with users distributed in governments, companies, enterprises and institutions. This operation mode of PAMR can give a full play to the advantages of trunking radio communications such as the sharing of frequencies, channels, coverage areas, communication services and expenses. Therefore, digital PAMR networks are becoming a development trend for future digital trunking communications.

GoTa Digital Trunking System
Global open Trunking architecture (GoTa) is the world's first CDMA-based digital trunking system launched by ZTE, and it is also the only one that complies with the standard released by China's Ministry of Information Industry. The GoTa system consists of the Base Station Subsystem (BSS), Dispatch Subsystem (DSS), Mobile Switching Subsystem (MSS), Packet Data Switch Subsystem (PDSS), terminals and Value Added Subsystem (VAS), as shown in Fig.1.


GoTa is a practical and professional 3G-oriented trunking service solution, optimized and improved at the basis of existing CDMA technology. It is designed with full consideration of PAMR features and various demands of commercial mobile users, and is capable of providing a variety of services to users such as radio dispatch, basic call, packet data services, as well as multiple value-added services like SMS and LBS. The new GoTa functions recently developed by ZTE include the following;

• All basic and supplementary services under the two modes of group call (traditional and enhanced group call)
• Roaming function to keep connection alive within the whole network
• Virtual DSS function that allows a single DSS to serve multiple areas
• Inter-fleet call and dynamic regrouping functions that enables easy collaboration between departments or fleets
• Open API interface of the GoTa dispatch console–to facilitate third parties to develop customized dispatch consoles
• Prepaid function to expand the billing capabilities of the GoTa system
• Automatic group information update
• Group call record query  

Benefits of ZTE's GoTa
While fully inheriting many benefits of CDMA technologies, the GoTa system can also offer professional radio dispatch functions. It has the following advantages;

• More advanced technology, higher spectrum utilization, and simpler network planning
• Clearer voice, higher capacity, more flexible services, and lower network construction costs
• Professional radio dispatch and high-speed wireless broadband access capabilities
• A full array of GoTa solutions covering the system, terminals, services and application models
• Possession of core technologies and independent IPR
• 3G service capabilities based on the 3G technical platform
• Feature-rich service applications

PAMR Features of GoTa
As the GoTa system is capable of delivering voice, PTT and data three major services, as well as value-added services, it is especially suitable to build PAMR networks, which offer varieties of services for both ordinary and enterprise users.

Radio dispatch services
The GoTa system has all radio dispatch functions of a professional analogue trunking radio system, capable of replacing the existing analogue systems. These functions include; 

• Basic trunking services; private call, group call, broadcast call, call priority, emergency call, group user priority, floor taken, late-entry and forced insert/release, and etc.
• Supplementary trunking services; call forwarding, group number presentation, calling number display restriction, call restriction, and etc.
• Virtual Private Network (VPN) services; fleet management, short number dialing, dynamic regrouping, terminal status query, dynamic group management, dispatcher services, and etc.

Featured trunking services

• Traditional group call
  It is implemented to support dense group calls in special cases or occasions, without any restriction in group capacity.
• Enhanced group call
  By taking advantage of high radio capacity of CDMA, the enhanced group call enables the system to monitor real-time status of each member in a group call, thus ensuring service reliability and making it possible to introduce new functions.
• Floor queue
  The system can line up floor request of the group members.
• User status query
  A user can query the on-line status of other members in the group.
• Service priority
  The operator can change priorities of the services. By default, trunking services have a higher priority than telephone services, and telephone services have a higher priority than data services.
• Group management 
  The group administrator can manage the group on a real-time basis using his or her own GoTa terminal, including both adding and deleting a user, setting user's priority and call duration.
• Do Not Disturb
  When a user is unable to join in the PTT call for a certain period due to personal reasons, he or she can set the trunking service to the Do Not Disturb (DND) status.
• Management console
  Through the management console, users and groups within the fleet can be managed. 
• Dispatch console
  Through the interface of the dispatch console, the dispatcher can implement fucntions such as calling users and groups, displaying the real-time status of group members, and checking calls.
• Positioning function of the dispatch console
  Integrating dispatch and positioning functions is a featured function of ZTE's dispatch console. A dispatcher can track the location of the dispatched user or group on a real-time basis while implementing private or group calls.

Voice services
The GoTa system offers all the CDMA 1X voice services, including related value-added services such as SMS and WIN.

Data services
The GoTa system supports 14.4 Kbps circuit data services such as G3 fax, low-speed Internet access, and low-speed data transmission, as well as 153 Kbps high-speed packet data services such as mobile office, video on demand, online query, multimedia mails and data industrial applications.

Location services
With a perfect combination of CDMA-based positioning technologies and trunking services, the GoTa system can offer featured and differentiated location service solutions, which can be widely used by industrial users and civil departments in areas of ship navigation, emergency assistance, vehicle management, goods tracking, logistics management, location-based charged service, and etc.

Conclusion
As GoTa can offer rich service functionalities, it is capable of providing end-to-end public trunking radio solutions. Today, GoTa has been used by operators in various countries such as China, Malaysia, Czech Republic, and Norway to provide PAMR services.