Configuring RTCP to Support Held Calls Using RR and RS Bandwidth Modifiers

Overview

This best practice provides guidance on configuring RTCP RR/RS Bandwidth modifiers from EMA to support held calls for a Multimedia Telephony Service for IMS (MTSI) environment as described on the page AMR and RTCP Enhancements..

Procedure

Configure Packet Service Profile on ePSX/PSX

1. On the SBC EMA main screen, go to Configuration > System Provisioning > Category: Call Routing > E PSX. The PSX manager window is displayed.

   PSX Main Window

   

   
   
   

2. In the PSX Manager window, choose Packet Service Profile from the fourth drop-down menu.

   PSX - Packet Service Profile

   

   
   
   

3. Choose the appropriate name of the Packet Service Profile configured to support RTCP from the sub-menu.

   PSX - Packet Service Profile - Sub Fields

   

   
   
   

4. Scroll down the display window to locate RTCP option.
   
   

5. Choose the RTCP option to enable it. This action enables the RTCP configurable flags.

   PSX RTCP - Fields

   

   
   The following parameters are displayed:

   All available parameters require RTCP to be enabled.

   PSX RTCP - Fields parameters

   Parameter	Length/Range	Default	Description
   RTCP	NA	Disabled	When selected, this option enables Real-time Transport Control Protocol (RTCP) for the channel. RTCP is used to report traffic congestion data.
   Packet Loss Threshold (Packets Lost/100,000 Packets)	NA	0	The packet loss threshold, measured in number of packets lost per 100,000 packets.
   RR Bandwidth	100-4000	250	The RTCP bandwidth allocated to active data senders.
   RS Bandwidth	100-3000	250	The RTCP bandwidth allocated for receivers.
   Packet Loss Action	NA	None	The action to take when the packet loss threshold is exceeded on the channel. Possible actions are: None—No action. Trap—Generate an SNMP trap. Trap and Disconnect—Generate an SNMP trap and disconnect the call. Trap and Adapt—(applies to GSX only) Generate an SNMP trap and invoke an adaptation mechanism.
   Enable RTCP Only For HELD Calls	NA	Disabled	If this parameter is enabled, SBC ignores the configured RR/RS values in the Packet Service Profile and send RR/RS = 0 in the offer/answer and disables RTCP when the call is active. When the call is HELD, and a RE-INVITE is sent,  the CPN (SBC) uses the configured values in the Packet Service Profile for RTCP bandwidth and enables RTCP. When the call is RESUMED, the CPN (SBC) again disables RTCP by sending RR/RS=0 in the RE-INVITE. If disabled the older behavior of SBC is applicable.
   Termination For Pass-Through Calls	NA	NA	When enabled, RTCP is terminated and generated locally even for pass-through calls.

   
   
   

6. Make the desired changes to these parameters.
   
   
7. Click Save to save the configuration.

Configure IP Signaling Profile on ePSX/PSX

1. On the SBC EMA main screen, go to Configuration > System Provisioning > Category: Call Routing > E PSX. The PSX manager window is displayed.

   PSX Main Window

   

   
   
   

2. In the PSX Manager window, choose IP Signaling Profile from the fourth drop-down menu.

   PSX Codec - IP Signaling Profile

   

   
   
   

3. Scroll down the display window to locate Common IP Attributes - Communicating With The Peer Regardless Of Call Direction section.
   
   

4. Enable the "Send RTCP Bandwidth Info" flag identified in the screen capture below:

   PSX IP Signaling Profile - Fields

   

   
   The following flag is now enabled:

   PSX IP Signaling Profile - Fields parameter

   Parameter	Length/Range	Default	Description
   Send RTCP Bandwidth Info	NA	NA	When this flag is enabled, the RR,RS bandwidth information, b=RR: and b=RS: is sent in the SDP offer.

5. Click Save to save your changes.