Ok, thanks azrobert (again)
For the record, the configuration I found (default after provisioning through obitalk)
FPL has MWI and VMWI enable, MessageWaiting was checked
GV has MWI and VMWI disabled (so this was ok already)
LP had MWI and VMWI enabled, MessageWaiting was unchecked. I disabled then, save and reboot.
I did have some new real VM. I listen to the VM (*98) and then deleted messages from FPL website.
Yet, MessageWaiting was still checked after 10+ minutes. Phone had stutter+"new messages"
By the way, it appears fpl can take up to 5 mins to update mwi per folks on forum.
So I finally forced "messagewaiting" to off....VM indicator on phone dissapear.... it came back by itself some 6 minutes later.
I will post on fpl forum. There was another user complaining about the same.
Thanks, like before I wouldnt be able to understand the problem / troubleshooting without your help