It is nearly impossible to replicate such setup here, maybe you need to contact support of the phone manufacturer? It seems the other models work fine, just one of them doesn't.
Certainly, I asked about it at Panasonic forums and several Panasonic dealers. Nobody knows.
It is clear that nobody will study a subtlety of interaction of the equipment of different firms.
Therefore I try to formulate here questions which experts Mikrotik can answer without consideration of Panasonic equipment.
On the other hand, differences in protocols of these models of phones was not detected whereas the difference in behavior of different versions of RouterOs is visible.
So, what I wanted to learn?
1. Somebody came up against this situation? As I understand, no. The question is closed.
2. Is there fw version more stable than 5.26 and 6.11? As I understand, no. The question is closed.
3. Whether the problem can be connected with that the ADSL channel, which, first, quite slow and, secondly, the asymmetric is used. We will notice that the sound doesn't pass in that direction in which the channel is weakest.
The third question obviously not for a begginers forum. I not really hope to receive here answer, but I plan to carry out a number of experiments. As a result, probably, we will either change the channel, or refuse from Mikrotik if other equipment shows the best results.
Obviously, I need to thank all for attention and to consider a subject closed.
I thank all for attention and I consider a subject closed.