Getting FQDN of Skype for Business (Lync) pool

[Reflection.Assembly]::LoadWithPartialName("Softerra.Adaxes.Adsi")

# Connect to the Adaxes service
$ns = New-Object("Softerra.Adaxes.Adsi.AdmNamespace")
$service = $ns.GetServiceDirectly("localhost")

# Bind to the user
$userDN = "CN=John Smith,CN=Users,DC=domain,DC=com"
$user = $service.OpenObject("Adaxes://$userDN", $null, $null, 0)

# Get the Registrar pool FQDN
$poolFqdn = $user.GetLyncPoolFqdn()

using Softerra.Adaxes.Interop.Adsi;
using Softerra.Adaxes.Adsi;
class Program
{
    static void Main(string[] args)
    {
        // Connect to the Adaxes service
        AdmNamespace ns = new AdmNamespace();
        IAdmService service = ns.GetServiceDirectly("localhost");

        // Bind to the user
        const string userPath = "Adaxes://CN=John Smith,CN=Users,DC=domain,DC=com";
        IADs user = (IADs)service.OpenObject(userPath, null, null, 0);

        // Get the Registrar pool FQDN
        IAdmLyncOps lyncOps = (IAdmLyncOps)user;
        string poolFqdn = lyncOps.GetLyncPoolFqdn();
    }
}