Headsets: https://www.headsetsdirect.com/yealink-headsets-everything-you-need-to-know-for-yealink-telephones
Default Credentials: admin / admin
OK
key on the face of the phone for 10 secondsor
0.us.pool.ntp.org
1.us.pool.ntp.org
These settings have the phone on VLAN 241 and the PC switch port as untagged.