User's Manual 556 Document #: LTRT-68822
Mediant 2000
Parameter Description

This feature can also be configured as an IP Profile and/or Tel
Profile.
Web/EMS: Enable Early
183
[EnableEarly183]
Enables the device to send SIP 183 responses with SDP to the IP upon
receipt of INVITE messages. This parameter is applicable to IP-to-Tel
(ISDN) and IP-to-IP calls, and applies to all calls.
 [0] Disable (default)
 [1] Enable
IP-to-Tel calls: By sending the 183 response, the device opens
an RTP channel before receiving the "progress" tone from the
ISDN side. The device sends RTP packets immediately upon
receipt of an ISDN Progress, Alerting with Progress indicator, or
Connect message according to the initial negotiation without
sending the 183 response again, thereby saving response time
and avoiding early media clipping.
IP-to-IP calls: Sending the 183 response enables SIP servers
that require a stream of early media, to keep sessions open.
Notes:
 To enable this feature, set the EnableEarlyMedia parameter to 1.
 When the BChannelNegotiation parameter is set to a non-Exclusive
value (Preferred or Any), the EnableEarly183 parameter is ignored
and a SIP 183 is not sent upon receipt of an INVITE. In such a case,
you can set the ProgressIndicator2IP parameter to 1 (PI = 1) for the
device to send a SIP 183 upon receipt of an ISDN Call Proceeding
message.
 This feature can also be configured in an IP Profile.
[IgnoreAlertAfterEarlyM
edia]
Determines the device's interworking of Alerting messages from PRI to
SIP.
 [0] = Disabled (default)
 [1] = Enabled
When enabled, if the device sends a 183 response with an SDP (due to
a received ISDN Progress or Proceeding with PI messages) and an
Alerting message is then received from the Tel side (with or without
Progress Indicator), the device does not send an additional 18x
response, and the voice channel remains open. However, if the device
did not send a 183 with an SDP and it receives an Alert without PI, the
device sends a 180 (without SDP). If it receives an Alert with PI it sends
a 183with an SDP.
When disabled, the device sends additional 18x responses as a result
of receiving Alerting and Progress messages, regardless of whether or
not a 18x response was already sent.
Note: This parameter is applicable only if the EnableEarlyMedia
parameter is set to 1 (i.e., enabled).
Web: 183 Message
Behavior
EMS: SIP 183 Behaviour
[SIP183Behaviour]
Defines the ISDN message that is sent when the 183 Session Progress
message is received for IP-to-Tel calls.
 [0] Progress = (Default) The device sends a Progress message.
 [1] Alert = The device sends an Alerting message (upon receipt of a
183 response) instead of an ISDN Progress message.
[ReleaseIP2ISDNCallOn
ProgressWithCause]
Typically, if an Q.931 Progress message with a Cause is received from
the PSTN for an outgoing IP-to-ISDN call and the EnableEarlyMedia
parameter is set to 1 (i.e., the Early Media feature is enabled), the
device interworks the Progress to 183 + SDP to enable the originating
party to hear the PSTN announcement about the call failure.
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