DND function not working across multiple accounts on Yealink T48S

[Polaris Networks]

Running 16.0.7.1078
Debian OS hosted on AWS Lightsail - London, Zone A (eu-west-2a)

Yealink T48S running 66.85.0.5
First account auto provisioned Direct SIP (STUN - remote)
Second account manually added.
Both accounts on same server.

Trunk Provider Zen Internet
Firewall checker passed
Not using custom templates

Amazon 3CX Server (Lightsail) > Internet > Router > PoE Switch > Handset

The issue we are seeing is that when using the DND soft button the phone intermittently either puts both accounts into DND (expected) or just the first or just the second.
Rebooting the phone or the 3cx server does not seem to change this behaviour
Factory resetting the phone and reprovisioning as above does not change this behaviour
This has repeated over two different phones (same model) on two different phone systems (both Amazon hosted). Networks at both locations utilised completely different hardware (Cisco Meraki & Draytek)

Does anyone else have any idea how we might be able to handle DND functionality reliably with two or more accounts on a single handset?

 

[JohnS_3CX]

Hi @Polaris Networks

We do not provide support for more than one account per device, so this scenario is untested with Yealink's 3CX firmware.

At the very least, the phone should behave as intended when provisioned as per our guides (using only 1 account per device).

You might need to contact the manufacturer for further details on how to handle multiple accounts, keeping in mind though that this may cause undesired behavior as you have already described above.