Anybody who has messed with DMR probably has obtained their DMR ID and subsequently made use of Brandmeister/Phoenix-DMARC/TGIF networks or some of smaller regional US side ones.
But it’s worth mentioning as both a reminder to DMR users and potential DMR users, that in the UK at least - an issued DMR isn’t a mandatory requirement for use of DMR legally under your license.
It’s more the case that to use any existing public ham DMR networks that without a registered issue ID, you’ll not have full comma access to the existing networks so making them relatively inaccessible by gateway/hotspot/repeater beyond listening usually in monitor/promiscuous mode (hence hearing all DMR traffic on the access frequency).
In fact, specifically focused on UK side, there’s both no legal formal requirements for an issued ID - if you don’t use an issued one, you’re just having to operate outside of the networks, but still - you’re free to use anything of a valid numeric combo (format wise) for direct localised group point to point simplex or even potentially via a non-gateway hotspot/repeater (so effectively just digital repeater operating equiv to analogue).
Provided you state and use your formal call sign as station ID during spoken QSO and calls and other transmissions, you’re legally covered within your license terms.
So, as far as prepping radios goes, say for a group operation (rally club members and stewards traffic use being an example), you could just put in any old chosen/invented ID in your radio, and put your call sign in as User. So in the club usage scenario, all that would be needed would be an agreed use of a given code to close the traffic to group only use (equiv to CTCSS closed squelch use in analogue) and the choice of whether (under agreement) to use open or common (standard) level encryption. Clearly you set a group number (TG) of some kind or just use the common one used for open simplex usage (so in the open sense, you’re using the colour code as a closed squelch equiv to analogue CTCSS usage).
As for encryption use, technically we’re not supposed to use any encryption at all on ham traffic, but it appears to be tolerated that common (standard on DMR) mode encryption is OK and used. Whether you use or not is down to you to live with, but definitely avoid AES/High Encryption mode usage as you’ll never be able to justify that as fair usage as HE usage is definitely intent use to heavily obscure traffic and that’s definitely a harshly applied slapped wrist misuse at best - worst case, well I guess someone will have a sad tale to tell over that eventually.
Also, for the sake of completeness, you can legally use any frequency in the ham allocation your radio is going to be configured for (usually 2m, 70cms, or dual if your radio is dual band), as the band plan conformity isn’t actually a requirement, it just is courteous and good practise to use the designated frequencies and subframes within for given types of operation/mode usage as suggested in the plan - some allocations used by hams use sub ranges rather than channelised style frequencies use - but 2m/70cms where DMR equipment is used is mostly channelised as far as commonly applied usage goes. Provided your usage falls within that permitted by the license schedule, you are legally covered.
However, that said, I’d still recommend sticking to band plan defined usage where possible. There are some necessary evil inclusions in the BP you’d want to avoid intruding on outside of BP recommendation such as avoiding the frequencies earmarked for space traffic and similar extreme QRP intended use.
But you could safely argue that since the delivery of digital voice is via telegraphic means, that usage (may be necessary during contest periods when many phone mode frequencies get heavily congested) of an earmarked telegraphy mode frequency is fair usage. I certainly wouldn’t contest that, just keep in mind that the courtesy minded will let the frequency be relinquished if it becomes apparent that people are trying to use the earmarked traffic mode or modes on it.
But generally, as long as you’re license compliant in how you use DMR in operation (until the license terms properly incorporate and formally ratify DMR and other DV modes/systems formally) then it’s down to you, your choice for localised group usage or as defined by the group your with if you’re not defining the group ops.
This may directly or in a limited fashion be applicable or not at all outside of the UK and UK Overseas territories. From my understanding, bar any specific overriding national restrictions, it should be the equivalent state of play across the EU (since we were part of it when DMR started getting used ham side).
Exactly how long DMR usage (as an EU ratified radio standard) remains legit in the UK remains to be seen, in main and ham usage, but I’d estimate it’ll remain as it’s more or less becoming the more used DV mode commercially since the alternatives (older and newer) are mostly expensive vs disposable cheap DMR TA certified gear in general.
Anyway, I’ll close this here as it’s moving away from the main subject.