Hoping someone can answer: Just received two refurbed Yealink T38G's for a customer to test. Their system is known working - Cisco SPA phones work fine from same IP address and ethernet port, v14 Pro. I can make and receive calls from the speakerphone, but the handset has no sound. Thinking I had a bad handset, I switched them. Thinking I had a bad phone, I switched that too. Provisioned or not, I cannot get sound out of the handset (other than a buzz....buzz....buzz, barely audible). I checked the handset level in the web interface. Tried different firmware to no avail. Do I just have two bad handsets or is there something obvious I haven't looked at? Thanks in advance for your help.