Hello Mac,
Confirm the follwoing details.
1)Can you confirm the IP and Vlan details for Vcenter , is it in the same segment as of ESXI host or the device from you are able to ping.
2)Did you checked with network Team , what was there feedback.
Need to check if the communication from Vlan segment of Vcenter is open for Voice Vlan, IF we can get it open or add a route and check.
Regards,
Anand Gowda.
Anand Gowda