welcome to the Polycom Community.
The Real Presence Mobile support page => here <= lists the difference between standalone and provisioned mode in the relevant release notes.
Calling the HDX or RPM within the same network via IP address will just work (depending on firewall rules) and no additional licenses are needed.
For more Information have a browse through the post here in the community.
Please ensure to provide some feedback if this reply has helped you so other users can profit from your experience.
Polycom Global Services
If official support is required please check how to phone or open a case here
The title Poly Employee & Community Manager is a community setting and does not
reflect my role. I am just a simple volunteer in the community like everybody else. All posts and words are my own & do not represent the views of Employer. ----------------
Notice: This community forum is not an official Poly support resource, thus responses from Poly employees, partners, and customers alike are best-effort in attempts to share learned knowledge.
Please also ensure you always check the VoIP , Video Endpoint , Microsoft Voice , PSTN or other FAQ's in the different sections