# CMP-FLOW-LEN — Message flow must be 40–2049 characters

> The opt-in / message-flow field must be at least 40 and at most 2049 characters.

- **Rule ID:** CMP-FLOW-LEN
- **Layer:** Campaign (`CAMPAIGN`)
- **Checks:** `campaign.message_flow`
- **Severity:** BLOCKING — Breaking this rule gets the submission rejected outright.
- **When it bites:** Gates approval — get this wrong and registration is refused
- **How it is detected:** Deterministic (settled in code from the submitted values)
- **Fix type:** Fix the field — a better value in the form clears it
- **Required by:** Twilio, TCR
- **Applies:** Applies to every 10DLC registration.
- **Canonical URL:** https://ekas.io/rules/10dlc/campaign/cmp-flow-len/

## Why this rule exists

The message flow has to hold the opt-in location, the consent wording, and a reference to the evidence, which does not fit in a sentence. The 2049-character ceiling is tighter than the description's, so a thorough flow can be truncated on submission without warning.

## How to fix it

Describe where and how consent is collected, including the exact disclosure wording shown to the consumer.

## Example of a compliant value

```text
Customers opt in at https://acmecoffee.com/signup by ticking an unchecked box reading "By checking this box, you agree to receive recurring automated marketing text messages from Acme Coffee…". Screenshot: https://cdn.acmecoffee.com/compliance/optin.png
```