Sip Server Name Resolution; Sip Server Name Resolution Configuration - Yealink SIP-T3 Administrator's Manual

Administrator's Guide for SIP-T2 /T3 /T4 /T5 /CP920 IP Phones
proxy server with different IP addresses when encountering a failover.
Note: It works only if "account.X.outbound_proxy.Y.failback_mode" is set to 1, 2 or 3.
0-Disabled
Permitted
1-Enabled, the phone will immediately re-subscribe to the secondary outbound proxy server, for ensur-
Values
ing the normal use of the features associated with a subscription (for example, BLF, SCA).
Default -1, the phone will invoke "account.X.sip_server.Y.failback_subscribe.enable" to take effect.
Parameter account.X.sip_server.Y.outbound_proxy_enable
It enables or disables the phone to use outbound proxy server address configured by "accoun-
t.X.outbound_proxy.Y.address".
Description
Note: It works only if "account.X.outbound_proxy_enable" is set to 1 (Enabled).
Permitted
0-Disabled
Values 1-Enabled
Default 1
[1]
X is the account ID. For T57W/T54W/T48U/T48S/T48G/T46U/T46S/T46G/T29G, X=1-16; for
T53W/T53/T53C/T43U/T42G/T42U/T42S, X=1-12; for T41P/T41S/T27G, X=1-6; for T33P/T33G, X=1-4; for
T40P/T40G/T23P/T23G, X=1-3; for T31P/T31G/T31/T21(P) E2, X=1-2; for T30P/T30/T19(P)
E2/CP920/CP925/CP935W, X=1.
[2]
Y is the server ID. For
T57W/T54W/T53W/T53/T53C/T48U/T46U/T43U/T42U/T33P/T33G/T31P/T31G/T31/T30P/T30, Y=1-3; for other
phones, Y=1-2.

SIP Server Name Resolution

If a domain name is configured for a server, the IP address(es) associated with that domain name will be resolved
through DNS as specified by
phone to adapt to various deployment environments. The IP phone performs NAPTR query for the NAPTR pointer
and transport protocol (UDP, TCP, and TLS), the SRV query on the record returned from the NAPTR for the target
domain name and the port number, and the A query for the IP addresses.
If an explicit port (except 0) is specified, A query will be performed only. If a server port is set to 0 and the transport
type is set to DNS NAPTR, NAPTR and SRV queries will be tried before falling to A query. If no port is found through
the DNS query, 5060 will be used.
Topic

SIP Server Name Resolution Configuration

SIP Server Name Resolution Configuration
The following table lists the parameters you can use to configure the SIP server name resolution.
Parameter account.X.sip_server.Y.transport_type
Description It configures the type of transport protocol.
0-UDP
1-TCP
Permitted
2-TLS
Values
3-DNS NAPTR, if no server port is given, the device performs the DNS NAPTR and SRV queries for
the service type and port.
342
RFC 3263. The DNS query involves NAPTR, SRV and A queries, which allows the IP
[1][2]
[1][2]
<MAC>.cfg
<MAC>.cfg