UK IPSC3 FAQ & Guide

What are the differences between IPSC2 and IPSC3?

IPSC2 provided the previous generation bridge and routing platform. IPSC3 is the locally developed replacement used by UK IPSC3 for live routing decisions, repeater and hotspot state tracking, dashboard visibility, talkgroup scan, private call routing, parrot support and stricter handling of edge cases that affected some radios.

For normal users, the aim is not to make operating more complicated. The aim is to make the network more predictable, easier to diagnose and more robust across Motorola IPSC repeaters, MMDVM hotspots, trunks and future integrations.

How do person-to-person private calls, roaming and timeslots work?

Make a direct, non-group call to the destination radio ID, normally on TS1. IPSC3 tracks where radios were last seen and automatically routes the call to the destination radio's current repeater, hotspot, approved trunk or POC endpoint. If the destination cannot be found within its roaming window, the caller receives a voice busy message saying the callsign or radio ID is unavailable.

Roaming keeps one current record for each radio ID, not a separate record for each timeslot. It records the last endpoint, last observed timeslot and last activity time. The latest accepted voice or data activity updates that record. Ordinary UK IPSC3 roaming currently remains valid for 12 hours, while Motorola ARS and POC use their own shorter online-presence rules.

Private voice calls should normally be started on TS1. IPSC3 then routes the call to the destination radio's last-seen endpoint and gives priority to its recorded timeslot. If no destination timeslot is known, the caller's timeslot is used. This means a call received from the caller on TS1 can be transmitted to the other radio on TS2, and a reply can be independently routed back to the caller's recorded TS1.

Simplex MMDVM hotspots always use their effective TS2. Duplex hotspots and repeaters use the destination's recorded timeslot. OpenBridge private calls use TS1, while POC has no physical RF timeslot and carries it only as routing metadata. If both radios are on the same endpoint, IPSC3 leaves the call local and does not translate it between timeslots.

Direct calls are independent of static or dynamic talkgroup camps. Stored and forwarded SMS is handled separately and is currently configured to transmit on TS2.

How do I get on the roaming list without kerchunking 235?

There are several ways to establish roaming without kerchunking TG 235, which can be annoying to other listeners when it is only being used to refresh your location.

If you have a Motorola radio with ARS enabled, IPSC3 can use that registration to keep your roaming entry current. If your radio sends GPS data, beaconing at a sensible interval such as 10 minutes can also keep roaming alive while providing useful position information.

If your radio has no supported data protocol to fall back on, roaming is registered from your last call and remains active on the last repeater or hotspot you used for the configured dwell window, normally 12 hours.

For a simple manual refresh, key TG 400 or use Parrot TG 9990 instead of 235. TG 400 cancels current dynamic talkgroups and also registers your roaming location. Parrot also registers roaming and gives you a useful audio check. Both are better choices than kerchunking 235 just to get onto the roaming list.

What is Scan Talkgroup 777 on TS1?

Key TG 777 TS1 from a repeater or hotspot to place that endpoint into scan mode. IPSC3 then listens for active traffic on UK IPSC3 and approved connected networks, and translates that audio back to TG 777 TS1.

If you reply on TG 777 TS1, IPSC3 sends your audio back to the last active talkgroup automatically. When that group goes quiet, the endpoint returns to scan mode. You can cancel scan by keying another talkgroup or TG 400.

What MMDVM hotspot options does IPSC3 understand?

IPSC3 currently recognises three custom options in the MMDVM options field. Option names are case-insensitive and multiple options can be separated with semicolons.

• ScanExclude=235,3801,3802,8409 prevents those talkgroups from being sent to that hotspot while it is in Scan Talkgroup 777 mode. This is a per-hotspot setting and does not affect normal direct or camped talkgroup use, and it does not affect other hotspots.
• ScanInclude=3801,3802 does the reverse: while that hotspot is in Scan Talkgroup 777 mode, only the listed talkgroups are allowed through. If both ScanInclude and ScanExclude are present, ScanExclude wins for any talkgroup listed in both options.
• TalkerAlias=Y enables outbound talker alias injection for that MMDVM hotspot using CALLSIGN - First Name from the radio ID database. It is off by default, and TalkerAlias=N keeps it explicitly disabled. Use this option with caution because talker alias can cause unexpected behaviour with some radios. If in doubt, do not use this option. Unsupported options are shown as Options Ignored in the hotspot hover/details so users can see exactly what IPSC3 is using.

Why can't I statically link every talkgroup under the sun on my hotspot anymore?

There were no supported multi-static hotspot setups on IPSC2 either. Hotspots configured that way were misconfigured, but the old system did not prevent it. That is one reason people were sometimes dragged unexpectedly to other talkgroups.

By design, UK IPSC3 has one static call channel, TG 235. Other user-selectable talkgroups are dynamic. A hotspot can only have one active talkgroup on a timeslot at any one time. For example, if 3801 and 3802 are both configured as static and both have activity, the hotspot can jump back and forth between them.

UK IPSC3 enforces the design rules of the network instead of accepting a configuration that creates unpredictable behaviour. It also gives audio and dashboard feedback when talkgroups are dynamically linked or unlinked, so you can tell where your hotspot is on the network.

If the aim is to listen across multiple talkgroups, use TG 777 TS1 scan mode. It provides a similar listening experience, but with predictable routing and a clear way to reply to the current active talkgroup.

On simplex hotspots, UK IPSC3 also mutes TG 235 while a dynamic talkgroup session is active. This prevents drag-back to 235 until the selected talkgroup times out. Simplex hotspots do not have multiple timeslots, so there can only be one active talkgroup at a time.

Does Parrot work on UK IPSC3?

Yes. Parrot on TG 9990 works with direct and group calls on repeaters, simplex hotspots and duplex hotspots. It records your audio, plays it back, then reads back your callsign if your radio ID resolves. If it cannot resolve your callsign, it speaks the radio ID in full.

What does UK IPSC3 do about hotspot drag-back?

UK IPSC3 knows the difference between simplex and duplex hotspots. When a simplex hotspot moves to a 380x or other dynamic talkgroup, UK IPSC3 mutes TG 235 and other competing traffic on that hotspot until the selected talkgroup has been quiet long enough to time out. This stops the hotspot being dragged back to TG 235 while you are trying to use another group.

Who runs the UK IPSC3 network?

The UK IPSC3 Network is administered by the OZ-DMR Team. The group is made up of licensed amateur operators who volunteer their time to supervise, maintain and improve the network for the amateur radio community. Repeaters and sites are also supported by local clubs, custodians and partner organisations.

How can I connect my repeater or get a repeater?

If you want to add a repeater to UK IPSC3, start by contacting the OZ-DMR Team via the OZ-DMR Network website. Include the proposed site, callsign, frequencies if known, internet access, power arrangements, coverage goal and who will act as custodian.

How can I report a bug or network problem?

For general user issues or beta feedback, report the problem through the OZ-DMR Team, the IPSC3 Discord channel, or by direct message to the IPSC3 maintainer if requested. For urgent repeater-site issues, also contact the local repeater custodian or club if known.

Useful bug reports include the time of the test, your radio ID, source repeater or hotspot, talkgroup, timeslot, what you expected to happen, what actually happened and whether the dashboard showed RX, TX, scan or private call activity.

Why might OZ-DMR Team not answer an on-air call during testing?

A lot of IPSC3 testing involves keying repeaters, hotspots or trunks with no audio path or no practical way to respond. If you hear testing activity and do not get a reply, assume testing is in progress rather than being ignored.