T58W Jerky Video from doorphone [Solved?]

[Xerox]

A video call from a Fanvil i62 doorphone is shown jerky, freezing into T58W phone.
Let's say moving image is shown at answer, then it freezes for 2-3 seconds then other few frames are shown then freezes again and so on, at regular intervals.
Of course i62 video is diplayed correctly on Fanvil phones or played as rtsp stream on VLC viewer.
A video call from Fanvil V67 is correctly displayed into T58W phone.
All is managed by Freepbx but it seems not to be the issue.
I played with doorphone/ip phone video bitrate without success.
Tried with another i62 doorphone, same issue.

Any suggestion ?