Yealink Yealink SIP-T28P, Administrator'S Manual

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Troubleshooting
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The IP phone only uses logo file in DOB format, as the DOB format file has a high
compression ratio (the size of the uncompressed file compared to that of the
compressed file) and can be stored in smaller space. Tools for converting BMP format to
DOB format are available. For more information, refer to
Yealink_SIP-T2_Series_T19P_T4_Series_IP_Phones_Auto_Provisioning_Guide
, available
online: http://www.yealink.com/DocumentDownload.aspx?CateId=142&flag=142 .
Press the volume key to increase or decrease the ringer volume when the phone is idle,
or to adjust the volume of engaged audio device (handset, speakerphone or headset)
when there is an active call in progress.
IP phones manufactured before February 2010 will use the power adapter preferentially,
while those made later will use PoE preferentially.
Auto provisioning refers to the update of IP phones, including update on configuration
parameters, local phone book, firmware and so on. You can use auto provisioning on a
single phone, but it makes more sense in mass deployment.
Plug and Play (PnP) is a method for IP phones to acquire the provisioning server address.
With PnP enabled, the IP phone broadcasts the PnP SUBSCRIBE message to obtain a
provisioning server address during startup. Any SIP server recognizing the message will
respond with the preconfigured provisioning server address, so the IP phone will be
able to download the CFG files from the provisioning server. PnP depends on support
from a SIP server.