All Call, Emergency, Scan, Roaming, and Priority, and how each one actually behaves on Conventional, IP Site Connect, Capacity Plus, and Capacity Max

In Article 1, we compared the four MOTOTRBO system architectures. But the architecture you choose isn’t just an infrastructure decision. It quietly determines how well features like All Call, Emergency, and Scan actually work when someone needs them. These are the features most overlooked in the design process, and often the ones that matter most on the worst day of the year.

Every one of these features exists, in some form, on every MOTOTRBO system. The difference is in reliability, reach, and control, and that difference is exactly what this article is about.

All Call

All Call is meant to do one thing: get an urgent message to every radio at once, regardless of what channel or talkgroup they’re on. In practice, how well it does that depends entirely on the system underneath it.

Conventional

Here’s the part that surprises a lot of people: a true All Call isn’t really possible on a conventional system. A broadcast only reaches radios sharing the same time slot as the person transmitting. Everyone else never hears it. Some organizations work around this with a scan list, but scanning doesn’t guarantee delivery; a radio that’s mid-conversation or listening elsewhere can simply miss it.

Capacity Plus

Trunking changes this completely. Capacity Plus supports one true, system-wide All Call that reaches every site and every user in the system. If every channel happens to be busy when the All Call goes out, TX Interrupt can step in and force it through by interrupting whatever else is happening.

Capacity Max

Capacity Max takes All Call further with real control over how it’s scoped: a message can go out to a single site, a group of sites, or the entire system, whichever fits the situation. There’s also a Broadcast Call option, where only the person who started the call can speak or end it. That’s useful for one-way announcements where you don’t want a channel devolving into cross-talk. And if the whole system is jammed with traffic, Capacity Max can automatically drop the least important ongoing call to let the All Call through, rather than simply queuing behind it.

Picture a fire breaking out on a production line. Without All Call, every worker who spots it tries to call it in separately, the channel floods with busies, and the emergency crew has to track down and relay instructions to each group individually, costing precious minutes. With All Call, one message reaches every radio on the system at once, and the emergency team responds without the delay of working around a jammed channel. That gap is exactly why All Call is worth designing for up front, not bolting on later.

Emergency Calling

Every MOTOTRBO radio can raise an emergency: by a dedicated button, a programmed button, or automatically if the radio itself detects unusual movement or inactivity. What happens next depends on the system.

On Conventional and IP Site Connect systems, an emergency typically moves everyone set to receive it onto a shared “revert” channel, where they stay until the emergency is cleared; if that channel is busy, TX Interrupt can force the call through. Capacity Plus and Capacity Max instead broadcast the emergency over a talkgroup, so people are notified no matter what channel they’re actually on and can keep their normal conversations going at the same time. Capacity Max adds one more layer: if the entire system is at capacity, it can automatically bump the least important active call to guarantee the emergency gets through.

Call Priority and Preemption

Not every call deserves equal footing on a busy system, and this is where the systems diverge sharply. Conventional, IP Site Connect, and Capacity Plus don’t have true call priority. The closest they come is TX (Transmit) Interrupt, which lets specific users override an in-progress call on the same talkgroup. Capacity Plus multi-site systems can also reserve a number of wide-area channels so calls between sites get preference over purely local traffic.

Capacity Max is the only architecture with genuine, built-in priority: Emergency calls and All Calls automatically jump the line, and individual talkgroups or users can be assigned their own priority level. When the system is full, Capacity Max holds calls in a queue rather than simply blocking them, and calls with priority or preemption rights can skip that queue entirely or be pushed to the front, guaranteeing they get through.

Scan

Scan lets a radio keep an ear on multiple channels or talkgroups without the user manually switching between them. That’s handy for supervisors, security staff, or anyone who needs situational awareness beyond their own group. But the way scan works changes meaningfully between architectures.

On Conventional systems, scan works sequentially: the radio hops from channel to channel down a list, briefly stopping if it hears traffic. That means it has to physically leave its current channel to check another, which can cause it to miss transmissions elsewhere, and constant scanning takes a toll on battery life. Capacity Plus and Capacity Max instead use Group Scan: the radio listens to every talkgroup on its list simultaneously, so it’s far less likely to miss overlapping calls. Capacity Max goes one step further, letting up to two talkgroups be flagged as priority so the radio will break away from a lower-priority call to catch them, and it can automatically pick up as many as seven talkgroups the moment it powers on.

Roaming

Roaming is what keeps a radio connected as a user physically moves between coverage areas. Without it, users would have to manually switch channels or zones every time they change locations.

A standalone conventional system has only one site, so roaming doesn’t apply. IP Site Connect and Capacity Plus multi-site systems both support it: the radio watches its own signal strength, and once it drops below a set threshold, it searches its site list for a stronger signal. That process can briefly interrupt an active call while it searches. Capacity Max improves on this by continuously sampling signal strength from known neighboring sites rather than waiting for a threshold to be crossed, which makes roaming noticeably faster, and it uses a separate handover threshold to avoid switching a radio away mid-call unless the new site’s signal is clearly better.

Taken together, these features are a good reminder that system design shouldn’t stop at coverage and capacity. A radio system that covers every corner of a facility but can’t reliably reach everyone in an emergency, or can’t let a supervisor’s call take priority when it matters, hasn’t actually solved the problem it was bought to solve.

Feature Comparison

Next in This Series

In Part 3, we’ll look at what happens behind the scenes to keep these systems running and secure: redundancy and failover, Subscriber Access Control, Stun and Revive, and the centralized management tools that set Capacity Max apart from the rest of the MOTOTRBO lineup.

View Article 1: MOTOTRBO Systems Explained ›

View Article 3: MOTOTRBO Redundancy, Security & System Management Explained ›

Contact Day Wireless Systems to start your MOTOTRBO system discussion.