Refer to the exhibit. Users report that outbound PSTN calls from phones registered to Cisco Unified Communications Manager are not completing. The local service provider in North America has a…

Question

Options

• Arule 1/^+1([^*!]+)/ \0/\1/
• Brule 1/^+1([2-9]..[2-9]....)$/\1/
• Crule 1/^+1([2-9]..[2-9]....)$/\1/
• Drule 1 /^+1([2-9]..[2-9]....)$/\0/

• A
  7% (2)
• B
  64% (18)
• C
  21% (6)
• D
  7% (2)

Explanation

Option B correctly strips the +1 prefix from the globalized E.164 format by using a capture group ([2-9]..[2-9]....) to isolate the 10-digit NANP number, then replaces the entire match with \1 - the captured group only - producing the 10-digit format the provider requires. The ^+1 anchors the match to the leading +1, and the $ ensures the remaining string is exactly 10 valid NANP digits.

Option A is wrong because its replacement string \0/\1/ is malformed - the \0 back-reference returns the entire original matched string (including +1), and the extra slash syntax produces an invalid output string rather than clean 10-digit dialed digits.

Option D fails for the same core reason: it uses \0 as the replacement, which outputs the entire matched expression (still including +1) rather than just the captured 10-digit group. A provider expecting 10 digits would receive +14085551234 instead of 4085551234.

Options B vs C - as presented, they appear textually identical; on the real exam the distractor difference is typically a space or syntax variation in the rule number separator, making only one syntactically valid in IOS.

Memory tip: Think \0 = whole match (zero edits, keeps everything), \1 = first capture group (your stripped/trimmed result). Whenever you need to remove a prefix, you must capture what you want to keep and reference \1, not \0.

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