I've recently tried using both the BeginGetAllMembers and BeginExpand methods of the DistributionGroup and they work fine when the distribution group had around 90 members. However, they both fail when I try a group with over 200 members. I
get an error in the End methods for each coming from 'Microsoft.Lync.Model.Internal.CBWBase.BlockUntilDone()'. I increased the MaxGroupSizeToExpand on the Lync server and that didn't help(http://social.technet.microsoft.com/Forums/en-US/ocsclients/thread/9c6fa06e-adfc-420a-a253-0c061dc16c83/).
I was wondering if the API has the same limitations as the server itself in that 150 is the limit for a group. I've been trying to use these methods to get all users in our company at once. Instead, as a temporary fix, I call the LyncClient.ContactManager.BeginSearch
method for each letter in the alphabet to get them all.