Tag: cme

Introduction I have recently had a strange issue with call transfers on CME 12.0. I was getting “SIP/2.0 488 Not Acceptable Here” from ISP while trying to transfer a call from PSTN to another extension. Let’s see how we can solve this problem and make the transfer work. Equipment Used The phone I used was

Introduction This article show step by step how to upgrade the firmware of a Cisco IP phone managed by CME(Call Manager Express). I will be upgrading Cisco 8851 IP phone(from version 12-0-1-11 to 12-5-1SR3-74) using Cisco ISR4331/K9 router as a CME. Step 1. Download the firmware files The first thing we need to do is