Phone Network
27
Parameters
DHCP
Option
Description
Router 3 Specify a list of IP addresses for routers on the client’s subnet.
Time Server 4 Specify a list of time servers available to the client.
Domain Name Server 6 Specify a list of domain name servers available to the client.
Host Name 12 Specify the name of the client.
Domain Server 15
Specify the domain name that client should use when resolving hostnames via
DNS.
Network Time Protocol
Servers
42 Specify a list of NTP servers available to the client by IP address.
Vendor-Specific Inform-
ation
43 Identify the vendor-specific information.
Vendor Class Identifier 60 Identify the vendor type.
TFTP Server Name 66
Identify a TFTP server when the 'sname' field in the DHCP header has been used
for DHCP options.
DHCP Option 66, Option 43 and Custom Option
During the startup, the phone will automatically detect the custom option, option 66, or option 43 for obtaining the
provisioning server address. The priority of obtaining the provisioning server address is as follows: custom option>-
option 66 (identify the TFTP server)>option 43.
The IP phone can obtain the Auto Configuration Server (ACS) address by detecting option 43 during startup.
To obtain the server address via DHCP option, make sure you have configured the DHCP option on the phone. The
option must be in accordance with the one defined in the DHCP server.
Note
If you fail to configure the DHCP options for discovering the provisioning server on the DHCP server, an alternate method
of automatically discovering the provisioning server address is required. One possibility is that connecting to the secondary
DHCP server that responds to DHCP INFORM queries with a requested provisioning server address. For more information,
refer to RFC 3925. If a single alternate DHCP server responds, this is functionally equivalent to the scenario where the
primary DHCP server responds with a valid provisioning server address. If no DHCP server responds, the INFORM query pro-
cess will retry and eventually time out.
Related Topic
DHCP Provision Configuration
DHCP Option 42 and Option 2
Yealink phones support using the NTP server address offered by DHCP.
DHCP option 42 is used to specify a list of NTP servers available to the client by IP address. NTP servers should be listed
in order of preference.
DHCP option 2 is used to specify the offset of the client’s subnet in seconds from Coordinated Universal Time (UTC).
Related Topic
NTP Settings
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