Rewrite: Caller ID & CNAM

[Manny-r31]

Current state

• Source file: /signalwire-fern-config/fern/products/platform/pages/calling/voice/caller-id-and-cnam.mdx
• Live URL: https://signalwire.com/docs/platform/voice/how-to-set-caller-id-or-cnam
• Page type (Fern): guide
• Approx. length: 78 lines (excluding frontmatter)

What's there today

• Opens with a three-paragraph explanation of CNAM vs. Caller ID (lines 11–18) that repeats the same distinction three times: "CNAM is name / Caller ID is number"; "CNAM is text / Caller ID is the number"; "Carrier references CNAM database separately."
• Four separate how-to sections (PSTN CNAM, SIP-to-SIP, SIP-to-PSTN, Verified Caller ID) with different workflows and constraints
• Heavy reliance on manual support-ticket process for PSTN CNAM setup (lines 32–38), requiring users to open Help > My Tickets (which should be support > my tickets)
• Multiple warnings and constraints scattered throughout (toll-free restrictions, Canadian CNAM, 15-char limit, 48-hour propagation, ID verification requirement)

Reviewer's concern

"One of the more common questions in tier 2. Could use a more concise rewrite."

Proposed rewrite

• New section structure (collapse verbosity, improve routing):
  1. "Caller ID vs. caller name": One to two paragraph explanation: Caller ID = the phone number displayed; CNAM = the name displayed with that number. CNAM only works on PSTN; for SIP, use Caller ID field in credential settings. Constraints listed inline (toll-free, Canada, 15-char, 48hr).
  2. Set CNAM (PSTN): Remains as is
  3. Set Caller ID (SIP): Combined SIP-to-SIP and SIP-to-PSTN under one section with a decision tree: "Send As" field for PSTN calls vs. "Caller ID" field for SIP calls. Link to SIP Endpoint settings docs.
  4. Verified Caller ID: Keep as is but adjust from SIP Credentials.