REFER-Initiated Call Transfer

The Oracle® Enterprise Session Border Controller supportes REFER-initiated call transfer either by proxying the REFER to the other User Agent in the dialog, or by terminating the received REFER and issuing a new INVITE to the referred party. These static alternate operational modes can be configured for specific SIP interfaces, realms, or session agents.

An additional operational mode can determine on a call-by-call basis whether to proxy the REFER to the next hop, or terminate the REFER and issue an INVITE in its stead.

The configuration parameter dyn-refer-term, and refer-call-transfer parameter specify call transfer modes.

With the refer-call-transfer parameter set to disabled (the default), all received REFERs are simply proxied to the peer User Agent.

With the refer-call-transfer parameter set to enabled, the Oracle® Enterprise Session Border Controller terminates all REFERs, generates a new INVITE, and sends the INVITE to the address in the Refer-To header.

With the refer-call-transfer parameter set to dynamic, the Oracle® Enterprise Session Border Controller determines REFER handling on a call-by-call basis as follows:

1. Check the refer-call-transfer value for the session agent from which the REFER was received, or for ingress realm (the realm that received the REFER).

   If the value is disabled, proxy the REFER to the peer User Agent, to complete REFER processing.

   If the value is enabled, terminate the REFER and issue an new INVITE to the referred party, to complete REFER processing.

   If the value is dynamic, identify the next hop egress realm.

2. Check the dyn-refer-term value for the next hop egress realm.

   If the dyn-refer-term value is disabled (the default), proxy the REFER to the next hop to complete REFER processing.

   If the dyn-refer-term value is enabled, terminate the REFER and issue an new INVITE to the referred party to complete REFER processing.