Administrator’s Guide for W60P DECT IP Phones
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Server Domain 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 RFC 3263. The DNS query involves NAPTR,
SRV and A queries, which allows the DECT IP phone to adapt to various deployment
environments. The DECT 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.
The following details the procedures of DNS query for the DECT IP phone to resolve the
domain name (e.g., yealink.pbx.com) of working server into the IP address, port and transport
protocol.
NAPTR (Naming Authority Pointer)
First, the DECT IP phone sends NAPTR query to get the NAPTR pointer and transport protocol.
Example of NAPTR records:
order pref flags service regexp replacement
IN NAPTR 90 50 "s" "SIP+D2T" "" _sip._tcp.yealink.pbx.com
IN NAPTR 100 50 "s" "SIP+D2U" "" _sip._udp.yealink.pbx.com
Parameters are explained in the following table: