Advanced Operational Features
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41-001343-02 REV05 – 07.2014
If
there
is no
Reason Header in the status message, the behaviour of the phone should be unchanged:
•
“Busy” is displayed for the status codes 486 and 503 (SERVICE UNAVAILABLE) and the busy tone will be played,
•
or “Call Failed” is displayed for status codes 4xx to 5xx and the call failed tone will be played,
•
or “Not Configured” or “Seize Failed” is displayed in case of an internal error,
•
or “Unavailable” is displayed in case of code less support (6735i, 6767i, 6755i, 6757i, 6757i CT, 6867i, 9480i, and 9480i
CT phones only).
Configurable “Allow” and “Allow-Event” Optional Headers
On the IP Phones, an Administrator can enable or disable whether or not the optional “Allow” and “Allow-Events” head-
ers are included in the NOTIFY message from the phone.
SIP NOTIFY messages from the phone may contain optional headers called “Allow” and “Allow-events”. If the NOTIFY
message contains these headers, the UDP packet returned by the server may be too large and may fragment the packet.
To prevent the fragmenting of the UDP packet, the “Allow” and “Allow-events” headers may be removed using the
parameter, “
sip notify opt headers
”. If this parameter is set to “
0
” (disabled), the optional headers are not included in the
SIP NOTIFY message which reduces the size of the packet returned by the server, and prevents fragmentation of the
packet.
The value set for this parameter specifies whether or not to include the optional headers in the SIP NOTIFY message from
the phone.
An Administrator can enable/disable the optional “Allow” and “Allow-Event” headers using the following parameter in
the configuration files:
•
sip notify opt headers
Enabling/Disabling Optional “Allow” and “Allow-Event” Headers
Use the following procedure to enable/disable “Allow” and “Allow-Event” headers.
Configurable SIP P-Asserted Identity (PAI)
The IP Phones support a private extension to SIP for Asserted Identity within trusted networks (as defined in RFC 3325).
This feature allows a network of trusted SIP servers to assert the identity of authenticated users, and verify that phone
messages originate from a Trusted Identity. Upon receiving a message from a caller in the Trusted Network, the IP phone
reads the contents of the P-Asserted-Identity (PAI) header field and displays it on the phone UI. This field contains
a more
accurate description of the caller identity (extension/phone number) than is contained in the SIP message.
When an IP phone receives an incoming call, the IP phone performs the following actions:
•
Checks to see if the incoming call is from a registered proxy server.
•
If the call is forwarded via a registered proxy server, then the message has already been verified and authenticated by
the server. The caller is part of the Trust Network. The IP phone UI displays the caller information contained in the PAI
Configuration Files
For the specific parameter you can set in the configuration files, see Appendix A, the section,
“Optional “Allow” and “Allow-Event” Headers”
Notes:
•
The phones support PAI header in the UPDATE message, according to draft-ietf-sipping-update-pai-00. This feature
is always enabled.
•
If an UPDATE is received with a PAI header from a trusted source, the phone updates the display with this information.
The phone ignores any PAI received from untrusted entities.
