Three MSCP systems with All Call?

This question came in the other day via my Blog's contact form:

I want to set up three capacity plus multi site systems in one area, because of the amount of channels and to have a dedicated set of repeaters for the essential channels. What I would like to know is, if there is a way to set up one All Call channel for that will trigger or send to all three systems? Or is there a better way of building it in a way that I can reserve specific sets of repeaters/rest slots for a sets of channels?

I assume you want to have that all non-transmitting radios; on all three systems, join the All Call(?)

One system

My first suggestion would be: why not create one single system and configure the radios and talkgroups so that everything stays in a specific region but the All Call goes out on all sites.

This would require each region to have unique talkgroup and radio IDs. The talkgroup-site assignment would allow the talkgroups in region A to go out over the sites for that region.

In the above example, sites 1 and 2 make up Region A; sites 3 and 4 Region B and 5 and 6 Region C. Talkgroups 1 and 2 (Call ID, left column) will only to the sites in Region A, Talkgroups 3 and 4 will only to the sites in Region B and Talkgroups 5 and 6 will only to the sites in Region C.

The radios would be configured to only roam on RF sites within that user's region. They would also be configured so that the user can only select talkgroups from their own region.

Click to enlarge

In the above example (although not the same as what is in the repeaters), when the user selects personality (channel-knob position) Talkgroup 3 or Talkgroup 4, the radio will only roam to Site 2. To expand the coverage of these two talkgroups, their Call IDs need to be ticked in the talkgroup-site assignment table of the Master Repeater and the radios need to have those sites added to the site list associated with those Talkgroups. 

Three linked systems

If it is not possible to create one single system, my other suggestion would be to use a dispatch application and patch the All Call on all three systems. This way, if an All Call is made on any one system, it is automatically routed through to the other two.

The advantage with this method, is that it would be possible to patch talkgroups as and when needed and that voice is passed between the regions without any conversion (DAD loss).

This method may prove more costly if you intend to use a dispatch application and want to make it 100% IP based (i.e. no control stations [a.k.a. donor radios]) since you will need one of Motorola Sold and Supported applications and all the repeaters will need a NAI Voice licence.

Control stations can be used if All Call is the only thing you are interested in. If that is the case, you don't need any of the Motorola Sold and Supported applications nor the NAI Voice licence. You will however need a control station in each region's system.

The disadvantage with using control stations is that they need to be within RF range of the site/system they serve and need to be linked back into the application server. Avtex have an Outpost; SmartPTT have a RG1000 and TRBONET have a Swift Gateway -  all three of these devices allow a remote donor radio to be linked into their respective radioservers via IP.

Using a control station (aka donor radio) is that you are only able to pass voice from a single talkgroup - or All Call in this case. The transmitting radio ID is not passed (only the IDs of the donor radios).

What is All Call.

In the case of Multisite Capacity Plus, All Call is a one way voice call to all radio (and dispatch) users on the system. The transmitting radio uses a dedicated talkgroup ID (255) that every radio will respond to. If all timeslots are busy with other calls, All Call can be used in conjunction with Transmit Interrupt.

 

DO NOT give All Call to just anyone.

The All Call feature should only be configured on selected radios and (if present) one or two dispatch consoles. Do not give this feature to users who cannot be trusted to use this responsibly. Abusing a feature like All Call results in user fatigue (i.e. people will stop paying attention to announcements).

Some additional thoughts.

There is a repeater feature called Reserved Wide Area Channels which will allow you to reserve a certain number of timeslots for wide-area calls that go out on more than one RF site - this feature also covers All Call. This might be useful but will reduce the system capacity for other types of calls.

The (new) Channel Blocked Override feature might also be useful if any of the sites are prone to interference.

If you are going to use Transmit Interrupt with All Call, you need to set this up in the personality. For this to work, it needs to be set up in all radios (i.e. the radio making the All call must be able to send TX Interrupt and all other radios need to be able to decode this).

Even though there is no call priority on MSCP, an Emergency Call is able to (impolitely) override an All Call.