Normally device updates are triggered after signing in to the Lync Server as described in detail in the previous article.But by adding the suggested configuration to a Lync 2013 server as outlined in this article then the issue can be avoided and devices can be updated as needed.
The device will then automatically perform a DNS query for the hostname for each domain name which may have been passed via those DHCP options.
Typically the certificate issued to the Lync Front End server is from an internal private Certificate Authority, which unfortunately means the device cannot automatically download the update without intervention.
This signals the intent to provide a single LPE client for both Lync platforms and not have separate 2010 or 2013 clients with different interfaces.
What this all means is that to utilize any Lync Phone Edition devices with Lync Server 2013 the phone firmware may need updated to at least the CU7 release, which is version 4.0.7577.4363 / .4366 / .4372 for different device families.
In these cases it will still be required to update Tanjay device in a two-step process to get to a supported version.
The oldest tested version which could successfully register to a Lync 2013 server is 3.5.6907.187.
Lync Phone Edition will only attempt to retrieve the root certificate from the internal, Active Directory published CA during registration attempts, it was not programmed to perform this same action automatically upon bootup.
So in this case user-intervention is required by attempting to sign-in to the Lync Server.
This confirms that the device does not inherently trust the certificate assigned to the Lync server so the root CA certificate which signed the Lync server certificate must be downloaded to the phone.