Establishing a connection with an XRF complex

An XRF complex can be a session partner.

There are two types of XRF complexes: those that use a USERVAR to manage sessions during an XRF takeover and those that use an MNPS ACB to manage sessions during an XRF takeover.

In either case, if the active IMS subsystem in the XRF complex fails, the alternate IMS subsystem re-establishes the session during takeover. Until the ISC session between the old active IMS and the remote system terminates completely, session initiation fails. Upon takeover, the alternate IMS subsystem becomes the active subsystem and retries session initiation every 30 seconds (for a maximum of 20 attempts) until the session initiates successfully.