I have an issue with a UC520 running vers. 7.1.3 with 504g phones running firmware 7-4-3. MWI is not working. I have read the other issues related to this and these don't seem to fit our issue. We have checked the Ephone-dn's and they are correct, we have checked the gateway and it is correct. Frankly, we're at a loss. Attached is the SIP debug. Any help you can provide is appreciated.