Situation: Mitel phone shows anonymous instead of the username.
Resolution: 1. Switch from soft phone to desk phone.
Resolution 2: Make sure the phone is setup correctly in the ShoreTel\Mitel server. in our case, the Primary phone port is setup 00-10-49-26-C5-C1, but it using 00-10-49-38-T5-09. Click GO PRIMARY PHONE that fixed the problem.