Yealink SIP- T28P User Manual

Troubleshooting
133
This chapter provides general troubleshooting information to help to solve the problems
you might encounter when using your SIP-T28P IP phone.
If you require additional information or assistance with your new phone, contact your
system administrator.
Why is the LCD screen blank?
 Ensure that the phone is properly plugged into a functional AC outlet.
 Ensure that the phone is plugged into a socket controlled by a switch that is on.
 If the phone is plugged into a power strip, try plugging it directly into a wall outlet
instead.
 If the phone is powered from PoE, ensure that you use a PoE-compliant switch or
hub.
Why does the LCD screen have bad contrast?
You need to adjust the contrast of LCD screen. To adjust the contrast, refer to Contrast on
page 19.
Why does the phone display "Network Unavailable"?
 Ensure that the Ethernet cable is plugged into the Internet port o the phone and the
Ethernet cable is not loose.
 Ensure that the switch or hub in your network is operational.
Why does the phone display "No Service"?
The LCD screen prompts "No Service" message when no SIP account registers
successfully.
Why doesn’t the phone display time and date correctly?
Check if you have configured the phone to obtain the time and date from the SNTP
server automatically. If the phone fails to connect to the SNTP server, you need to
configure the time and date manually.
How do I find the basic information of the phone?
Press the OK key when the phone is idle to check the basic information of the phone,
such as the IP address and firmware version. For more the basic information, refer to
Phone Status on page 14.

Yealink SIP- T28P Specifications

General

Expansion module support	Yes
Ethernet LAN (RJ-45) ports	2
Keypad number of keys	48
Voice codecs	G.711, G.722, G.723.1, G.726
Handset type	Wired handset
Product type	IP Phone
Product color	Black
Touchscreen	-
Display resolution	320 x 160 pixels
Lines quantity	- lines
Phonebook capacity	- entries
Number of VoIP accounts	6
Bluetooth	No
Security algorithms	HTTPS, SSL/TLS
AC adapter input voltage	100 - 240 V
AC adapter output voltage	5 V
Power consumption (typical)	2.6 W
Operating relative humidity (H-H)	10 - 95 %
Compliance industry standards	IEEE 802.3af
Number of handles included	1 pc(s)

Weight and Dimensions

Depth	204 mm
Width	273 mm
Height	42 mm
Weight	1050 g