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This configuration is not supported on ERE and is intended for use with an external PSX and/or ePSX only.

Voice over LTE (VoLTE) is a technology for providing existing voice and SMS services over LTE which does not have a circuit-switched domain. It is implemented using IP Multimedia Subsystem (IMS), which is a standard 3GPP technology for IP-based multimedia services. One of the key requirements of the Roaming Architecture for Voice over LTE with Local Breakout (RAVEL) as described in 3GPP TS 23.228, 3GPP TS 24.229, and as proposed in 3GPP TR 23.850, is that the  Interconnection Border Control Function (IBCF) supports Optimal Media Routing (OMR) procedures and allows bypassing the Transition Gateways (TrGWs).

The 3GPP TS 29.079 describes the procedures for optimizing the media path for call within IP Multimedia Subsystem. The purpose of OMR is to identify and remove unnecessary media functions from the media path for each media stream associated with a session. The OMR procedures identify and name the IP address realm used for each media path segment among UAs and TrGWs. An IP realm name is associated with each set of IP endpoints that are mutually reachable through IP routing and without address translation. Endpoints in different IP realms usually require allocation of a TrGW between those IP realms for connectivity and possibly for NAT.

Prior to OMR procedures, the SBC supported direct media between endpoints residing in the same media zone. With the implementation of OMR procedures, the SBC is enhanced to perform media path optimization even when direct media is not possible between end points by allowing intermediate nodes to be bypassed for media anchoring. SBC supports OMR procedures in IBCF and P-CSCF roles.

The realm parameter is used with an Address Context object to define realm names for use in OMR procedures.

For feature functionality, please see OMR and TRF Support.

For configuration best practices, see Configuring SBC to Apply OMR Rules.

Command Syntax


% set addressContext <addressContext hame> realm <realm name> connectedRealm <list of up to 10 connectedRealm names> 

Command Parameters

Table : Realm Parameter






1-32 characters

<realm name> – A unique realm name.

  • connectedRealm <connectedRealm list> – A optional list of up to 10 connected realms. Realm names can contain up to 32 alphanumeric characters.

When configuring the SBC to use OMR, realm must be configured. However, connectedRealm is optional.

Command Example

admin@SBC01a% set addressContext default realm myRealm connectedRealm Realm1,Realm2,Realm3

admin@SBC01a% show addressContext default realm
realm myRealm {
    connectedRealm Realm1,Realm2,Realm3;