I solve the problem without help.
You asked me to ask whoever set it up, but that company went to bankrupt so I did it myself.
I cannot share my experience because you gave me no help for me.
I upgrade the phone myself, and prevent the downgrade problem on polycom side.
Thank you so far.
Hello Mingeon Kim,
You did not provide this information and again I did tell you to upgrade the phone.
The rest of the Information is freely available within this community.
I am closing this post.
Polycom Global Services