Which of the following fields should you configure to enable calls from this Cisco Jabber client to be rerouted through the PSTN if bandwidth is lacking?

A. AAR Group

B. Location
C. Rerouting Calling Search Space
D. SUBSCRIBE Calling Search Space
E. Use Trusted Relay Point

Explanation:

You should configure the AAR Group field to enable calls from this Cisco Jabber client to be reroutedthrough the public switched telephone network (PSTN) if bandwidth is lacking. Automated Alternate Routing (AAR) Group configurations enable calls to be rerouted to specified destinations when Cisco Unified Communications Manager (UCM) blocks a call becausebandwidth is lacking. AAR Group profiles are configured by navigating to Call Routing > AAR Group in UCM Administration. After you have configured a profile, you can assign it to an endpoint by selectingthe profile from the AAR Group dropdown field on the Device > Phone configuration page for the given endpoint.

You should not configure the Location field. The Location field is used to configure call admission control (CAC). CAC is used to limit bandwidth available for audio and video calls between locations, thereby regulating the quality of those calls. The location of Hub_None, which is used in this scenario, indicates that UCM is not monitoring the bandwidth that this particular endpoint is using. Locations can be configured by navigating to System >Location in UCM Administration. After locations have been configured, you can apply the configuration to an endpoint by selecting it from the Location dropdown field on the Device > Phone configuration page for the given endpoint.

You should configure neither the Rerouting Calling Search Space field nor the SUBSCRIBE Calling Search Space field. A search space is an ordered list of partitions that a device is allowed to search for patterns that match a given string, such as a dialed number. The Rerouting Calling Search Space field determines the route to a refer to target. The target is specified in a Session Initiation Protocol (SIP) Refer message. The SUBSCRIBE Calling Search Space field, on the other hand, is used to route Presence subscribe requests froman endpoint.

You should not configure the Use Trusted Relay Point field. A Trusted Relay Point (TRP) is a transcoder or media termination point (MTP) device that UCM considers to be the closest to a given endpoint if multiple resources are required for the endpoint. When this option is configured to the Default setting, the endpoint uses a common device configuration to determine the TRP setting. If this option is configured to Off, UCM will not attempt to use a TRP for the endpoint regardless of the common device configuration. If this option is configured to On, UCM will attempt to use a TRP for the endpoint regardless of the common device configuration.

Reference:
Cisco: Automated Alternate Routing Group Configuration