A phone has a device CSS that includes the partitions phones and PSTN.This provides access for all internal phones and external calls.The first line on this phone has a CSS that includes the…

Question

Options

• ANo,because the CSS on the line does not include the partition for long-distance.
• BNo,because when there is a CSS on both the line and the device,the line CSS takes precedence.
• CYes,because the line CSS also includes the <None> partition and this will be used to match the
• DYes,because the call will use the device CSS

• A
  5% (2)
• B
  3% (1)
• C
  14% (5)
• D
  78% (29)

Explanation

Option D is correct because in Cisco Unified Communications Manager (CUCM), when both a Line CSS and a Device CSS are configured, they are combined - the system searches the Line CSS partitions first, and if no match is found, it then searches the Device CSS partitions. Since the long-distance call doesn't match any partition in the Line CSS (phones, 911, local), CUCM falls through to the Device CSS, where the PSTN partition matches and completes the call.

Why the distractors are wrong:

• A is wrong because it assumes the call is limited only to what's in the Line CSS - it ignores that the Device CSS is also searched as a fallback.
• B is wrong because "line CSS takes precedence" means it is searched first, not that the Device CSS is discarded - both are searched in sequence.
• C is wrong because the <None> partition logic doesn't apply here; the Device CSS already provides the necessary PSTN partition match.

Memory tip: Think of Line CSS and Device CSS as a two-layer net - the Line CSS is the top layer (searched first), and the Device CSS is the bottom layer (catches what falls through). A call only fails if neither layer contains a matching partition.

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