Is there something like RUI/RUA in MOTOTRBO?

[Q] In the UK, emergency services use TETRA based units, which in the ambulance service usually consists of 3 radios 'tethered' to a callsign - two handhelds for the crew, and a base unit in the ambulance itself.

We use a lot of point to point calling - control can call each radio individually, or commonly used (and the point of this question) is they can ring all three at the same time, opening a talk path private call with whichever radio answers by pressing the PTT.

I am part of a private ambulance event service, who wishes to do the same - we have UHF repeaters, R7's and DM4600e as base units.

So, in essence, the question is - how do we do the above - can we put each 'lot' of radios in a group and have them all private called at once, with whichever radio answers the call. Hope this makes sense !.

[A] Before anyone gets excited, I’m no TETRA expert. I also have no information about the Airwave TETRA network.

TETRA has two features called Radio User Assignment (RUA) and Radio User Identity (RUI) and this is what I think the UK emergency services are using. Using this, the personnel would sign into the network using (I’m guessing) the vehicle’s fleet number or registration number. This, in effect, associates their radio numbers (Individual Short Subscriber Identity or ISSI) with the vehicle.

The 999 call centre presumably has a dispatch application that processes this RUI/RUA information and allows the dispatcher to make a call to the vehicle (all three radios) without needing to know the ISSI or which personnel are onboard.

RUI/RUA is reliant on several components in the TETRA network and would not work if the radios were used in direct mode; on a repeater or on a base station in local site trunking mode. It is also standardised in ETSI TR 102-300-5 and is also a requirement for obtaining interoperability. 

There is nothing like RUI/RUA in DMR. However, MOTOTRBO has two features that will do the same as RUI/RUA from a user point of view:

On conventional systems, in combination with a dispatch application, Sign-in/Sign-Out allows a user to sign in to a dispatch application using a username. Here is a written description from TRBONET and a Video from DTS showing it in action. There is also a Wiki page on this.

On Capacity Max systems, the Username Verification feature works in the same way but will also associate the user with their system access rights (e.g. which sites they are allowed to access, what priority they have etc.). Here is the Wiki page which goes into some detail on this feature.

Remember that Username Verification and Sign-In/Sign-Out will only work between the dispatcher and radios. If one radio user wants to make a private call to another radio user, they will need to dial the number (or select the contact list entry). Also, when one of these radios make a talkgroup call, their Radio ID; Alias or Talker Alias will be displayed on other radios.