Hello Sx,
welcome to the Polycom Community.
It is always useful to include the currently used UC Software version as issues experienced or a question asked may already be addressed in a newer release.
Please also include if you are using a SIP server or a LYNC / Skype for Business server.
If not LYNC / Skype for Business please provide us details what SIP platform is being used and in addition what type of Directory.
This also allows yourself and others to check against current software release notes, Administrator Guides or FAQ post’s.
The above is also stated in the "Read First"
Therefore the Polycom VoIP FAQ contains this post here:
Question: How can I find out my SIP or UC Software Version of my Phone?
Resolution: Please check here
Please ensure to provide some feedback if this reply has helped you so other users can profit from your experience.
Best Regards
Steffen Baier
Polycom Global Services