I have a Mitel 5312 IP Phone running in SIP mode. I am trying to change the Tone Code from "US" to "GB" via the web interface - admin tools - network config. I enter "GB" in the Local Tone Code box and click on the Save & Reboot button. When I go back to check, the Local Tone Code has reverted to "US" and I am still unable to use the tones and ringing cadence used in the UK.
I am using firmware R7.2.02.00.00.31 Any help would be much appreciated. Thank you.