There appear to be some changes in the V28 patterns over the past few days. It is possible these activities have been occurring in the past and are just now being noticed.
For example, this morning, Dec 9, 2105, both 3277 kHz and 3689 kHz were used. The "normal" V28 came up at 1330 UTC on 3277 kHz, it continued until about 1340 UTC. At the same time, 1330 UTC, 3689 kHz became active with some type of voice traffic, but not the normal V28 format. 3689 kHz ended quite early but the carrier stayed on air, possibly this was just test audio at 1330 UTC. And then, at 1340 UTC and after 3277 kHz was complete, the voice form 3277 kHz shifted to the transmission on 3689 kHz, and sent a brief message. Nothing was seen on 3052 during this mornings events.
Additionally, over the past few days the message on 3277 kHz has been shortened, so that only about 5 minutes of important audio was sent, vs the 10 minutes in prior use.
When numbers stations are new it is not uncommon for them to change format until they settle into a format they can use for all occasions. It is possible that V28 is still I the early days of its operation and details are still being polished as needed.
T!