The old AT&T phones (Yealink) require additional configuration to fully work with the Grandstream UCM.\\

Requirements:\\

__Timezone__ \\

The timezone must be manually configured to -6 UTC for CST, then location set to United States for DST. \\

__SIP Account Setup__ \\

The SIP setup for the extension is pretty standard. Extension number and password from the UCM. Endpoint 10.141.0.2.\\

__Voicemail Config__ \\

Yealink phones don't know how to contact Grandstream voicemail by default. In order to receive voicemail notifications, you have to go to Account -> Advanced -> Subscribe for MWI. This is set to on, and voicemail is set to *97. I typically add a soft key for Voicemail under Dsskey.\\

__Directory / LDAP Config__ \\

The directory config is the most complicated.\\

Enable LDAP: Enabled\\
LDAP Label: PPS\\
LDAP Name Filter: `(\\
LDAP Number Filter: `(\\
LDAP TLS Mode: LDAP\\
Server Address: 10.141.0.2\\
Port: 389\\
Base: dc=pbx,dc=com\\
Username: admin\\
Password: admin\\
Max Hits: Default\\
LDAP Name Attributes: cn sn displayName\\ 
LDAP Number Attributes: telephoneNumber\\ 
LDAP Display Name: %cn\\
Protocol: Version 3\\
LDAP Lookup for Incoming Call: Enabled\\
LDAP Lookup for Callout: Enabled\\
LDAP Sorting Results: Default\\

__T48S Phone__\\

The T48S model allows a background to be uploaded. See link: {{:phone_configuration:phone_background.png?direct&400|}}