Yealink IP Phones Configuring Guide 
76 
Destination Port 
(Listening port) 
Description of destination port 
IP address of 
DHCP server 
DHCP protocol port, it is used to 
obtain IP address from DHCP 
server. 
IP address of 
LDAP server 
Determined by the 
destination device. 
LDAP protocol port, it is used to 
obtain the contact information 
from LDAP server. 
NTP protocol port, it is used to 
synchronize time from NTP time 
server. 
IP address of 
syslog server 
Syslog protocol port, it is used 
for IP phones to upload syslog 
information to syslog server. 
IP address of PNP 
server (Default 
value: 224.0.1.75) 
Protocol port, it is used to obtain 
the URL of updating file from 
PNP server. 
HTTP port (default value: 80) 
HTTP port (default value: 443) 
SIP protocol port, it is used for 
signaling interaction with the SIP 
server. 
RTP protocol port, it is used by