Which of the following search spaces is used by every VoIP endpoint by default? (Select the best answer.)

A.
a custom device search space

B.
a custom line search space

C.
the <None> search space

D.
both a custom device search space and a custom line search space

Explanation:
The <None> search space is used by every Voice over IP (VoIP) endpoint by default. A search space is an
ordered list of partitions that a device is allowed to search in order to locate patterns that match a dialed
number. A partition is a logical grouping of VoIP route patterns and directory numbers (dns). A device that is not
able to match a dialed number in any of the search spaces that are assigned to the device will generate a busysignal. However, every VoIP endpoint can match a route pattern or dn that is contained within the <None>
search space.
The <None> search space contains the <None> partition. The <None> partition initially contains all the dns that
are configured in the VoIP network. Therefore, you should move route patterns and dns from the <None>
partition to a custom partition to limit specific pattern matching to specific endpoints. Cisco recommends that
you not leave dns in the <None> partition, because doing so could enable users to dial numbers that you intend
to restrict.
Custom device search spaces and custom line search spaces are not used by every VoIP endpoint by default,
because custom search spaces must be created by an administrator before they can be assigned. By default,
only the <None> search space initially exists in Cisco Unified Communications Manager (UCM). A device
search space is a search space that is assigned to a device itself. The information in a device search space will
be searched no matter which line on a device is chosen for the outgoing call. A line search space, on the other
hand, is a search space that is assigned to a single line on a device, not to the device itself. The information in
a line search space will be searched when the user chooses the line to which the search space is assigned as
the outgoing line for the call.
If a device is configured with both a device search space and a line search space, the device will combine the
two search spaces together, with the line search space taking precedence. Thus the information that is
contained in the line search space will be searched first. For example, if you assign a search space named
Local to the IP phone itself and a search space named LongDistance to a line on the IP phone, the
LongDistance search space will be searched first and a user will be allowed to make long distance calls from
the IP phone. Cisco recommends configuring calling search spaces at the device level to prevent users from
bypassing calling restrictions by simply placing calls from an alternate phone line.

https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/8_0_1/ccmsys/accm-801-cm/
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