Creating and Modifying Media Lists

In this section:

Name/description for the Media List.

Specifies a list of Media Profiles to be used in this Media List.

The order of the codec profile controls the order in which the codecs will be listed in the SIP message(s) sent to the peer. They should be listed in the order of user preference; the more desirable codecs listed first (above). The following are options to move/add/edit  the profile:

• Up. Moves the profile up in the list.
• Down. Moves the profile down in the list.
• Add/Edit. From the Select Media Profile box, click to select a profile and click OK. The profile is added to the list.
• Remove. Removes the profile from the list.

 

Specifies the Managing SDES-SRTP Profiles to be used with this Media List.

Specifies the DTLS-SRTP Profile to be used in the Media list. DTLS-SRTP is an extension of the Datagram Transport Layer Security (DTLS) protocol and is used to negotiate SRTP keying between the SBC 1000/2000 and Microsoft Teams over the UDP media port.

Options in the drop down list are derived from the configured DTLS-SRTP Profiles on the SBC. Refer to Working with DTLS-SRTP Profiles.

Each Media List is configurable with the DSCP value to be used for media flow. All media flows that are created using this media list share the same DSCP value. Typically, a SIP Signaling Group selects the media list to be used for the calls using that Signaling Group. The default value is 46 and the allowed range is [0..63]. The configured value should be chosen according to the QoS policies of the IP network traversed by the media packets.

Specifies either RTCP or RTCP-XR usage for this profile

RTCP: The 

sends basic RTCP messages to the peer.

RTCP-XR(Extended Reports): The RTCP-XR packets have more information, however, some SIP endpoints may not be handle the \-XR packets, in which case basic RTCP should be specified.

RTCP-XR (Real Time Control Protocol - Extended Reports) provides packet transport quality metrics. The metrics are designed to supplement the packet-loss metric in RTCP and the roundtrip delay measurement provided by RTCP. They provide metrics for IP Packet Delay Variation based on the IPDV metric defined in, metrics reporting the activity of the RTP end system's receiver's jitter buffer, and metrics reporting "errored" and "severely errored" seconds.

For more information about this topic, see RFC 5093.

Specifies whether or not to use RTCP-based Dead Call Detection (DCD).

DCD is accomplished by monitoring incoming RTCP packets. If this feature is enabled, and if no RTCP packets are received from the peer for a period of 30 seconds, the call will be considered "dead", and disconnected. DCD should be disabled if the peer does not send RTCP packets.

Specifies where or not to use Voice Activity Detection and send PT13 packets when on.

• If Silence Suppression is enabled, the 
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  monitors outgoing audio (towards the IP network). If silence is detected, voice packet transmission will cease to save network bandwidth. The enable setting saves network bandwidth, however, voice quality may be slightly degraded.
• If Silence Suppression is disabled, voice packets are sent regardless of whether or not audio is present.

Allows you to control the gain or loss (in decibels) to either the received or transmitted signals.

• Negative values represent signal attenuation (lower volume)
• Positive values represent signal amplification (higher volume)

Specifies the gain or loss in decibels to apply to received signals. (Packet → PCM direction).

Specifies the gain or loss in decibels to apply to transmitted signals (PCM ← Packet direction).

Specifies whether or not modem passthrough is enabled when using the G.711 codec.

If the user wants to support modem calls, this option should be Enabled. When Disabled, the 

does not distinguish between voice and modem calls. When Enabled, and the  detects a modem call, it switches to Modem Passthrough mode (based on G.711 codec).

Controls whether or not the 

supports G.711 faxing.

• If you wish to force fax calls to use G.711 (uLaw/aLaw) codec, then Fax Passthrough must be Enabled. Also, G.711 must be the only codec in the
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  Media List. In this configuration, the 
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  will only offer/accept G.711 in the reINVITE.

• If you wish to support both G.711 and T.38 faxing simultaneously, the Fax Passthrough must be Enabled, and the 
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  must be configured with both G.711 and T.38 codecs. Which faxing type is selected will depend upon the codecs offered/accepted in the reINVITE.

• If you wish to force fax calls to use T.38 codec, configure the Fax Passthrough to Disable. The 
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  must be configured for both G.711 and T.38 codecs. In this configuration, the 
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  will only offer/accept T.38 in the reINVITE.

Specifies whether or not the 

will detect Fax tones produced by the origination side fax machine. CNG tone detection is used when Fax calls are received from TDM to a Fax server and the voice call needs to be switched to a Fax call using T.38. If CNG tone detection is enabled, the  detects the Fax tone from TDM and switches to Fax mode (it will initiate a re-INVITE with T.38 support to the Fax Server). If CNG tone detection is disabled, the  will pass-through the Fax tones to the Fax server and the Fax server will have to detect them and initiate a re-INVITE to switch to Fax mode with T.38.

Specifies whether or not the 

system will detect Fax tones produced by the terminating side fax machine. Fax tone detection(V.21 flags) is used when Fax calls are received from TDM to a Fax server and the voice call needs to be switched to a Fax call using T.38. If Fax tone detection is enabled, the  detects the Fax tone from TDM and switches to Fax mode (it will initiate a re-INVITE with T.38 support to the Fax Server). If Fax tone detection is disabled, the  will pass-through the Fax tones to the Fax server and the Fax server will have to detect them and initiate a re-INVITE to switch to Fax mode with T.38.

Normally, resetting the SBC Edge resets the DTMF Signal-to-Noise ratio to 0. This field allows you to permanently set the value from -3 dB to +6 dB.

Enables configuration for the DTMF minimum level threshold. Valid entries: -48 to -14 dBm0. Default entry: -38 dBm0.

Specifies how DTMF digits are passed through the data network; as normal voice or encoded as specified in RFC 4733 (RFC 2833).

RFC 4733 (RFC 2833): When a DTMF digit is detected in the voice stream coming from the TDM side, the digit is removed from the voice stream (going to the IP network), and is sent out-of-band using the RFC 4733 (RFC 2833) mechanism.

As Voice: The DTMF digits are sent in the voice stream without any special treatment.

Specifies the payload type used for RFC 4733 (RFC 2833) packets. Available only when RFC 4733 (listed as RFC 2833) is specified for Relay Type.