I have tried as well and as far as I can tell it won’t work until either
[list]
Snom specifically add support for it
The meter maid patches/feature gets implemented in asterisk 1.4
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The asterisk logs always complained there weren’t hints for my extensions.
I upgraded two of my servers from 2.1.1 to 2.1.3. The third had 2.1.3 installed so I had to rerun ./install_amp.
When I type “sip show subscriptions” in the CLI it now shows all my subscriptions.
My snom phones running firmware 6.2.2 and 6.2.3 are now showing the state of subscribed extensions. I am not using 6.5.1 because I found a bug with Transfer on Hook always staying on even if set to off. Hope they fix this in the next firmware.