Using private call is not encrypted it's just not routed publicly through the BM servers


Private call is DMR user ID to user ID, it can not be monitored on hoseline or by a third party, no 3 way just two users
When you send someone a private call keep in mind private calls take priority so if the person you're calling is in an active QSO somewhere on the network it will pull them off that QSO regardless of what talk group they were on so it's a good idea to let the person know a head of time that you want to private call them
You do not need to have either DMR ID programmed into the radio, private calls are not used by RX groups lists and can be manually dialed or selected from your contact list or talk group list

Some DMR radios have talk group hold trimmers that can be adjusted to accommodate private calls either by manual dial or from your list, if you plan on receiving private calls you need to have the talk group private call hold timer set long enough to keep your radio from switching back to the original talk group you were using before you received the private call

For example if you're in an active QSO on say 3100 and someone sends you a private call, your device whether it be a hotspot or repeater will immediately switch you off that talk group and into private call when you answer your radio will be locked into the private call, however if your private call hold timer is set too short your radio could go back to the original talk group you were using,
to avoid this set the hold timer to at least 30 seconds If there is a gap in between the QSO greater than 30 seconds or whatever you set the hold timer to the radio will leave private call and return to the original talk group. You could store the DMR user ID of the person and set it to private call as a channel that way you can return to the QSO anytime.

An interesting observation I made recently using private call to someone who was on a local DMR repeater, we were using a local talk group as normal and the repeater had that talk group in auto static with the 15 min hold timer then it dropped, I sent a private call and that call was routed to the repeater, so apparently private calls are sent to your last know device
Per BrandMeisters policies Master Servers Administrators shall NOT: Block private calls, unless specifically requested by repeater sysop,
most all repeaters I have used do not block private calls but note you will be tying up a time slot on the repeater, people we see the green LED flashing on thier radios indicating the repeater is in use