• Group Calls (or Talkgroup Calls)

This is the default mode of communication within the NSW GRN.  They allow a user to contact all members of a particular talkgroup at the one time, even though members of that talk group may be dispersed across wide geographical locations within the GRN coverage area, or all converged at the one location. This type of call is appropriate for dispatch or fleet communications, allowing a central dispatcher to simultaneously communicate with their entire fleet.

• Private Calls (One-to-One Calls)

Users are also able to make private one-to-one calls to any other radio within the network (irrelevant of geographic location or talkgroup), simply by dialling that radio’s unique identification number. No other users will hear the conversation, thus allowing a private conversation to take place similar to that of a normal telephone or mobile phone (although still in half-duplex mode).

• Telephone Interconnect

Users also have the capability of making calls into the telephone network (known as telephone interconnect calls), allowing any telephone to be called. The radio's alphanumeric keypad is used to dial the required telephone number. This facility is individually enabled in each radio upon request to the NOCC.  It should be noted that these calls are in half-duplex mode. Appropriate charges apply.

• Duress (or Emergency) Call

Each radio can be programmed with a duress (or emergency) button. Activation of this button causes

• an immediate alert to be sent to the user’s central dispatch or Operations Centre
• an immediate alert to be sent to all users on the same talkgroup, making them aware of the user’s emergency or duress.
• an immediately raise in the priority of the user's call above that of others on the network (this means that on a busy site, the call goes to the beginning of the queue, rather than the end of the queue).

Furthermore, if the user's radio has been temporarily disconnected for tactical reasons, the use of the duress button over-rides the disconnection for the duration of the duress call.

Duress calls remain active until cleared down by the user who initiated the call.

• Multi-Group Calls

Similar to Group Calls, this capability allows a user to contact all members of a number of selected talkgroups simultaneously, again despite geographical location. This also includes the use of ‘Emergency Service Organisation (ESO)’ talkgroups that allow joint operations and interoperability between agencies.  Most agencies do not use multi-group calls, and instead join together talkgroups via a patch on a Centracom or console when required.

• Call Priority

The network also has the capability of allowing the prioritisation of talkgroups. There are 10 possible levels of call priority. Priorities are usually only changed during a crisis or an emergency to give relevant agencies a higher priority according to their needs throughout the event. It should be noted that call priority only comes into affect for a busy site with queued calls.   Calls are queued in priority order.  If the site is not busy, then the call is processed like any other.

• Call Alert Page  

This feature is a means for a user to determine if the radio of another user is switched on and within radio coverage. When a Call Alert Page is issued, the network attempts to locate the required radio, and if found, a positive acknowledgment message is sent to the initiating radio as confirmation. The message "PAGE RECEIVED" is shown in the display of the radio that has just been contacted. If the required radio was not found, a negative acknowledgment message is sent to the initiating radio.

• Radio IDs

The ID of a calling radio is shown in the display of a user's radio at the beginning of each call to assist in identifying the source of the call.  The ID of the radio can be found by going to the private call feature and scrolling left or right to "MY ID".  More is discussed about IDs here.

• Out of Range Indication

This message notifies the user that they are outside the network coverage area.

• Site Trunking Indication

This message notifies the user that wide-area communications is currently not possible. Communications can only be made to users who are affiliated to the same network site.

• Radio Inhibit for lost/stolen Radios

Due to the unique numeric identification that is given to each radio, it is possible for the NOCC to inhibit and disable radios if reported lost or stolen. A radio’s programming can be completely erased through the use of a ‘Kill’ command issued from the NOCC, thus making the radio totally unusable and completely barred from the GRN.

• Digital Encryption

After completion of digitisation of the network, users will have the capability to send and receive digitally encrypted messages (where implemented by the agency), ensuring even higher levels of security than is already inherent within the trunking technology.  Digitisation of the network includes replacement of all handsets, upgrading network infrastructure and replacement of analogue links  that connect remote sites to the central switching infrastructure.

• Guaranteed Grades of Service

The Network Manager is required to meet contractual Service Levels as set down by the NSW Government. This includes the requirement to provide a Guaranteed Grade of Service and network availability.