Hi, user_3433189!
You can check whether the following information
is correct:
1. The VLAN or 802.1x is incorrectly set. As a
result, the network between the gateway and the IP phone is disconnected.
On the login screen of an eSpace 79XX series
phone, choose Apps > Advanced > Network > Network Access and set the 802.1x or VLAN parameters.
2. If the SIP server address is the domain name, check whether the DNS server address is correctly configured on the IP
phone.
I hope to have helped you!