H.323 Endpoint Shows Registered on the VCS Control and Unregistered on the Endpoint

Introduction

This document describes how to troubleshoot an issue where an endpoint tries to register to the Video Communication Server (VCS) via the H.323 signaling protocol and the VCS shows registered, but the endpoint shows unregistered.

Contributed by Ishan Sambhi, Cisco TAC Engineer.

Problem

The endpoint shows registered on the VCS control, but unregistered on the endpoint. This packet capture from the endpoint shows that the endpoint sends the Registration_Request (RRQ) out, but does not receive the Registration_Confirm (RCF).

This VCS packet capture shows that the VCS sends the RCF to the endpoint, however the RCF never reaches the endpoint.

Solution

On the VCS, the endpoint shows registered as from the VCS's perspective it has sent  the RCF. However, since the endpoint does not receive a RCF it shows unregistered on the endpoint.

This is usually a firewall issue, where UDP port 1719 might not be open from the VCS to the endpoint or because the RCF is dropped on the network between the VCS and the endpoint.