Custom Support and MS quarterly earnings

From https://view.officeapps.live.com/op/view.aspx?src=https://c.s-microsoft.com/en-us/CMSFiles/TranscriptFY17Q3.docx?version=67911bdd-8f38-bbeb-c163-d1a908d07735 : "As expected, Enterprise Services revenue declined 1 percent and was flat in constant currency, due to a lower volume of Windows Server 2003 custom support agreements."

I did not even know that Custom Support has to do with MS quarterly earnings until today! I wonder how much it actually costs for MS.