Hello Mingeon Kim,
welcome to the Polycom Community.
It is always useful to include the currently used SIP or UC Software version as issues experienced or a question asked may already be addressed in a newer release.
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
In addition these are just outgoing calls?
If this is just certain numbers and all other outgoing calls are fine then I would guess your service provider is at fault.
Please follow this up with them?
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
