Yealink SIP-T38G Administrator's Guide

Configuring Advanced Features
155
The IP phone picks the first record, because its order of 90 is lower than 100. The pref
parameter is unimportant as there is no other record with order 90. The flag ―s‖
indicates performing the SRV query next. TCP will be used, targeted to a host
determined by an SRV query of ―_sip._tcp.example.com‖. If the flag of the NAPTR record
returned is empty, the IP phone will use "sip:user@example.com" for the next NAPTR
query.
SRV (Service Location Record)
The IP phone performs a SRV query on the record returned from the NAPTR for the host
name and the port number. The sample of the SRV records for reference:
Priority Weight Port Target
IN SRV 0 1 5060 server1.example.com
IN SRV 0 2 5060 server2.example.com
Parameters are explained in the following table:
Parameter
Description
Priority
Specify preferential treatment for the specific host entry. Lower
priority is MORE preferred.
Weight
When priorities are equal, weight is used to differentiate the
preference. The preference is from highest to lowest. Again,
keep the same to load balance.
Port
Identify the port number to be used.
Target
Identify the actual hosts for an A query.
The two SRV records point to different hosts. The two records have the same priority 0.
The weight of the second record is higher than the first one, so the second record is
picked first. If there is no IP address returned in the response, the IP phone sends out an
A query to look up the IP address. So in this case, the IP phone will use
"server1.example.com" and "server2.example.com" for the A query.
A (Host IP Address)
The IP phone performs an A query for the IP address of the target host name. The
sample of an A record for reference:
IN A 62.10.1.10

Yealink SIP-T38G Specifications

General

Expansion module support	Yes
Ethernet LAN (RJ-45) ports	2
Keypad number of keys	48
Touchscreen	-
Display resolution	480 x 272 pixels
Display number of colors	16.78 million colors
Lines quantity	- lines
Phonebook capacity	1000 entries
Number of VoIP accounts	6
Voice codecs	G.711, G.722, G.723.1, G.726
Bluetooth	No
Security algorithms	802.1x RADIUS, HTTPS, SSL/TLS
AC adapter input voltage	100 - 240 V
AC adapter output voltage	5 V
Power consumption (typical)	4.6 W
Operating relative humidity (H-H)	10 - 95 %
Handset type	Wired handset
Product type	IP Phone
Product color	Black
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