Yealink SIP-T21 E2 Administrator's Guide

Administrator’s Guide for SIP-T2 Series/T19(P) E2/T4 Series/T5 Series/CP860/CP920 IP Phones
50
3. Press or , or the Switch soft key to select the Enabled from the Static DNS field.
4. Enter the desired value in the Pri.DNS and Sec.DNS field respectively.
5. Press the Save soft key to accept the change.
A dialog box pops up to prompt that the settings will take effect after a reboot.
6. Click OK to reboot the phone.
DHCP Option
DHCP provides a framework for passing information to TCP/IP network devices. Network and
other control information are carried in tagged data items that are stored in the options field of
the DHCP message. The data items themselves are also called options.
DHCP can be initiated by simply connecting the IP phone with the network. IP phones
broadcast DISCOVER messages to request the network information carried in DHCP options,
and the DHCP server responds with specific values in corresponding options.
The following table lists common DHCP options supported by IP phones.
Parameter
DHCP Option
Description
Subnet Mask
1
Specify the client’s subnet mask.
Time Offset
2
Specify the offset of the client's subnet in
seconds from Coordinated Universal Time (UTC).
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
Information
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.

Yealink SIP-T21 E2 Specifications

General

Brand	Yealink
Model	SIP-T21 E2
Category	IP Phone
Language	English