Polycom IP 320 Administrator's Manual page 198

Administrator's Guide for the SoundPoint IP / SoundStation IP / VVX Family
Attribute
voIpProt.SIP.outboundProxy.address
voIpProt.SIP.outboundProxy.port
voIpProt.SIP.outboundProxy.
transport
A - 18
Outbound Proxy <outboundProxy/>
This configuration attribute is defined as follows:
Permitted
Values
dotted-deci
mal IP
address or
host name
0 to 65535
DNSnaptr or
TCPpreferre
d or
UDPOnly or
TLS or
TCPOnly
Default Interpretation
Null IP address or host name and port of a SIP
server to which the phone shall send all
requests.
5060
DNSnapt If set to Null or DNSnaptr:
r If voIpProt.SIP.outboundProxy.address is a
hostname and
voIpProt.SIP.outboundProxy.port is 0 or
Null, do NAPTR then SRV look-ups to try to
discover the transport, ports and servers, as
per RFC 3263. If
voIpProt.SIP.outboundProxy.address is
an IP address, or a port is given, then UDP is
used.
If set to TCPpreferred:
TCP is the preferred transport, UDP is used if
TCP fails.
If set to UDPOnly:
Only UDP will be used.
If set to TLS:
If TLS fails, transport fails. Leave port field
empty (will default to 5061) or set to 5061.
If set to TCPOnly:
Only TCP will be used.
NOTE: TLS is not supported on SoundPoint
IP 300 and 500 phones.