Actually, you are talking about radio IDs here. When Unitrunker shows an "I" in the "T" column (T = Type, IIRC), the value shown under "Group ID" is a radio ID because that is a direct radio-to-radio call, not involving a talkgroup at all. (I = Individual Call.)
I only gave a little demonstration of the 8xxxxx and 7xxxxx formats to help illustrate that the same numbers can be "used over again" in both talkgroup IDs and radio IDs.
If you see an I-call with a source (Radio) ID of 12345 and a target (Group) ID of 23456, it's not going to talkgroup 23456, it's going to radio 23456. T4Win used 'source' and 'target' nomenclature, if I recall correctly; it's a bit better description, IMO, than 'radio' and 'group', especially in this case.
When a Motorola system's control channel announces a call, be it a group call or an individual call, it actually "speaks" in hexadecimal. So if radio 12345 was calling talkgroup 23456, it says something similar to "3039 G 5BA0". (That's not exactly how it goes, but it serves to illustrate the point.) If a radio asks for an individual call/private call to another radio, the G is replaced with an I. So you could theoretically see the same thing, except with an I in it - "3039 I 5BA0" ... that would mean radio 12345 was calling radio 23456 directly. Has nothing to do with talkgroup 23456 at all.
The values showing up under the "Group" heading during I-calls are logged (I'm reasonably sure they are), just not in the GID file. Since they're actually radio IDs, they belong (and are) in the RID file.
gmclam - change your display settings to have the system show you "Motorola" style IDs (under the "Options" menu) and you'll see the numbers in the 7xxxxx/8xxxxx format I described. Other than hex, that's the "natural" way Motorola radios see these values internally.
Unitrunker (Rick) - Am I on target with how Unitrunker handles this?