The Government recently changed the NSW communications network used by a multitude of emergency and non-emergency agencies.

This includes private companies such as Electric Companies, shopping centres and any other companies with the need to communicate over long distances via two-way radio.

Its using technology called P25 (Project 25) but is also referred to as APCO25 and is now the national standard in New South Wales and some other states.

Those systems are referred to as Trunked Systems - remember that term. Trunking is an essential part of the PSN or previously GRN.

The latest upgrades have seen the PSN move to the Phase II system. The full technical description is APCO25 Phase I or II.

While some systems still use Phase I a majority of broadcast towers have now been upgraded (or enabled) Phase II. Some temporarily run on both systems at the same time. However, in order for a hobbyist to continue to listen to the PSN and its users, a Phase II capable scanner is an absolute requirement.

If you are in the market of buying a scanner ensure it is capable of receiving APCO25 digital AND Phase II. Otherwise all you`d be able to listen to is Aviation, the occasional user still on Phase I and CB radio communications.

While Phase I provided flexibility and a lot of talkgroups for a great number of users, the PSN would run out of space so to speak. To keep things simple, Phase II is a natural evolution of the P25 network.

It allows users to use a more advanced vocoder - AMBE2+ allowing audio to pass through a more compressed bit stream. Additionally to allow for more capacity, Phase II allows two voice channels to pass through within 12.5kHz radio frequency bandwidth.

Phase II is also backwards compatible allowing the system to be rolled back should the need arise.

When in operation and used by agencies, talkgroups allow the logical grouping of radio users to ensure they can communicate with each other. Inside a talkgroup sharing takes place to allow all radio users of a specific talkgroup to speak to one another and to the operator if applicable.

If a user in for example the SES broadcasts a message in one of their assigned talk groups, all other users on that talk group are able to hear that message.

Think of it like a WhatsApp group. In scanning context this is important as we must know who the talkgroups belong to, label each talk group and categorize it to understand who is being listened to.

The NSW Police force went ENC (encrypted) in the mid 2010s. This stops unwanted listeners to monitor those talkgroups, the unintended side effect is that the lack of oversight may breed corruption, coverups and secrecy.

Everyone agrees that some channels are not meant for public ears such as special operations groups, drug enforcement, etc. However for most others it is merely a nuisance.

Encryption works by using cryptographic algorithms, a topic which is complex but in simple terms, there are several different types of encryption methods such as end to end, Asymmetric Encryption and Symmetric Encryption.

Keys to decode the encrypted voice channels are changed frequently and nearly impossible to break. Most importantly it is also HIGHLY illegal and any successful person with for example a stolen radio would get caught within hours as your location would be broadcast to everyone on that encrypted talkgroup.

I am not a lawyer but expect to spend many years in jail. Please do NOT email us asking how to decrypt transmissions. Those emails are marked as spam.

The control channel is like the backbone of the entire system.

Firstly there are voice channels. Those - as the name suggests carry the communications between users.

However the control channels carry a lot of digital packets with critical information, they are used for resource allocation, setting up calls between units (when PTT is in use), channel assignment and system management ( load balancing for example).

If you fail to program the correct control channels, you will get nothing but garbled tones - that is the data mentioned above.

Radio IDs (RIDs) on the NSW Public Safety Network (PSN) are unique identifiers assigned to individual radios or devices operating on the network. They help track, manage, and distinguish each radio during communications. A Radio ID (RID) is a numerical identifier assigned to each radio handset, mobile unit, or console connected to the PSN.

These IDs are transmitted during voice or data activity and are visible to dispatch consoles and scanner software. RIDs are typically 5 to 7 digits long. For example, a SES NSW unit use ID range 204#### - 206####, while NSW Police radios use 021#### - 219#### range.

The NSW Public Safety Network (PSN) currently covers over 540,000 km²—about 67% of New South Wales—with expansion underway to reach 85% land coverage.

• • • • • Current Reach: Covers 540,000 km², including metro, regional, and remote areas

        • Target Availability: 99.95% uptime for emergency services

        • Expansion Goal: Increase to 85% land coverage across NSW