.. _arch-PBR: Architecture ------------- :ref:`phone-based-registration-feature-reference` The VOSS-4-UC Phone Based Registration Add-on is implemented as a `Cisco Unified IP Phone Services Application <https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cuipph/all_models/xsi/9-1-1/CUIP_BK_P82B3B16_00_phones-services-application-development-notes/CUIP_BK_P82B3B16_00_phones-services-application-development-notes_chapter_01001.html>`_. This operates a web service on the VOSS-4-UC platform that is installed on all unified nodes in a VOSS-4-UC Cluster as follows: |PBR-Network.png| Figure 1: Phone Based Registration Network Connectivity .. |PBR-Network.png| image:: /src/images/PBR-Network.png