Where is calling party transformation most appropriately applied for PSTN calls?

• A. Route Pattern
• B. Translation Route
• C. Dial Plan
• D. Calling Party Mask

Answer: (A)

The key idea is controlling what number the PSTN sees as the caller ID when outbound calls exit your network. The place to enforce that control is at the outbound routing decision, which is the route pattern. By attaching a calling party transformation to a route pattern, every call that matches that pattern is transformed in the same way before it goes to the PSTN, ensuring a consistent and correct presentation of the caller ID.

Translation routes focus on changing the digits you dial, not the information the PSTN receives as the caller ID, so they’re not the right mechanism for CLID control. A dial plan defines overall numbering and routing structure but doesn’t apply per-call CLID transformations by itself. A calling party mask is a specific masking option and doesn’t offer the broad, centralized application you get by using a transformation on the route pattern.