Introduction

Overview

Advanced IP industrial phones such as the X6U may fail to place a call on hold or transfer it on certain PBX platforms. This is because the X6U includes video capability in its SDP, while some PBX systems do not support video negotiation for this model. As a result, the PBX may reject the re-INVITE used for hold or transfer with a 4xx or 5xx response.

Applicable Models

X6U/X210/X7C/X7/X7A/X3V/C600.

Intended Audience

This document is intended for internal R&D staff, customers using these IP phones, and test personnel who want to understand how hold and transfer issues on advanced IP industrial phones can be resolved.

Solution Steps

Disable video on the phone. As shown below, log in to the phone web interface, go to Phone Settings--Function Settings-and set the default answer mode to Audio.