Yealink T46u is a SIP / VOIP phone, configure the phone to use the account / server settings of your VOIP provider, check their website there are normally instructions as to how to configure the VOIP settings.
Make sure the Yealink T46u is getting an DHCP IP address from the Hub, try with Google DNS 8.8.8.8 and 8.8.4.4 to ensure VM's Websafe filters can not block your VOIP connection.
Note a product like the Yealink T46u can not be used with a VM home phone service, this requires an analogue telephone plugged into a classic BT style of wall socket or into the TEL 1 port of the Hub.