Unable to register 8851 with Webex using registration code

[Paul Austin]

OK so trying to register a bunch of 8851 phones with Webex, code has been generated from Control Hub, entered into phone but just get "Server certificate validation failed" when adding to workspace BUT get "Invalid Code" when trying to add the same phone to a person. The on-boarding code is valid, network has been checked for NTP (Meraki) and there are no firewall rules. Phone code is 14.X.X. I have seen some posts about invalid Manufacturer certificate but it isn't clear if I am hitting that AND how to actually fix it.

Fairly new to all this ATM.

Any Ideas please?

[Jonathan Schulenberg · Accepted solution]

Did you migrate the phone from CUCM Enterprise to MPP firmware required by WxC-MT? That firmware version implies not. 
https://upgrade.cisco.com/e2m_converter_wxc

https://help.webex.com/en-us/article/n19c71/Migrate-Your-Phone-to-Webex-Calling

[Paul Austin]

Yes, Just after I had posted I realised - hey thats the wrong phone software.

Thanks