Image exchange chat
The supported values are included in the following table.In Lync 2010, user photos are managed on the server by the Address Book Service.The corresponding in-band provisioning parameter for Display Photo and Max Photo Size KB is named Photo Usage.Values for the Photo Usage parameter are send to clients through the endpoint Configuration provision Group.
Next, after retrieving the image file, Lync 2010 client compares the attribute values returned from the query against the attribute values received by the client from in-band provisioning to see if they are different.
User photos in Lync 2013 can be up to 648 pixels by 648 pixels with a file size of up to 20 MB.
High-resolution photos in Lync 2013 must be located in the user's mailbox on Exchange 2013, and are supported only with Lync 2013 client.
Lync client gets user photos by first querying the Address Book Web Query (ABWQ) service on the server, which is exposed through the Distribution List Expansion web service.
The client receives the image file and then copies it to the user's cache to avoid downloading the image each time it needs to be displayed.