Mitel 6867i Administrator's Manual page 612

Mitel 6800 Series SIP Phone Release 4.2.0 Administrator Guide
CONFIGURATION
FILE VALUE
1
2
Note: On the phone side, if you configure the phone with a Fully- Qualified Domain
Name (FQDN) proxy and specified port, the phone always sends "A only" lookups to
find the Host IP Address of the proxy.
6-34
DNS SERVER DESCRIPTION
METHOD USED
SRV & A The phone issues requests for "SRV" (Service Location
Record) records from the DNS server to get the port number.
Most often, the IP address is included in the response from
the DNS server to avoid extra queries. If there is no IP
address returned in the response, the phones send out the
request for "A" records from the DNS server to find the IP
address.
NAPTR & SRV & First, the phone sends "NAPTR" (Naming Authority Pointer)
A lookup to get the "SRV" pointer and service type. For
example, if Global SIP transport protocol on the phone is
"UDP", and Proxy server on the phone is "test.mitel.com",
then:
1. If the NAPTR record is returned empty, the phone will use
the default value "_sip._udp.test.mitel.com" for the "SRV"
lookup.
2. If the NAPTR record is returned "test.mitel.com SIP+D2U
.... _sip._udp.abc.mitel.co m", the phone will use
"_sip._udp.abc.mitel.com" for the "SRV" lookup.
3. If the NAPTR record is returned "test.mitel.com SIP+D2T
.... _sip._tcp.test.mitel.com", where the service type TCP
mismatches the phone configured transport protocol
"UDP", the phone will ignore this value and use the default
value "_sip._udp.test.aastra.com" for the "SRV" lookup.
Note: The phone does not use the service type sent by the
NAPTR response to switch its transport protocol, nor does it
use the NAPTR response to determine whether to use a
secure or insecure communication path. The phone will
always use a global sip protocol that is configured on the phone
via configuration files or the web user interface.
After performing NAPTR, the phone sends "SRV" lookup to
get the IP address and port number. If there is no IP address
in the "SRV" response, then it sends out an "A" lookup to get
it.