# OPS-142 — A legitimately shared number needs a register of who sends on it

> Where a number or short code is shared under an approved arrangement, documented records of every message sender operating on it must be immediately available.

- **Rule ID:** OPS-142
- **Layer:** Operational (`OPERATIONAL`)
- **Checks:** `shared-number sender register`
- **Severity:** HIGH — Rejected by at least one carrier or provider, and a common cause of failure at the rest.
- **When it bites:** Falls due after approval, once you are live and sending
- **How it is detected:** Not knowable before submission — reported with its deadline
- **Fix type:** Supply evidence only you hold
- **Required by:** T-Mobile, CTIA
- **Applies:** Applies to every 10DLC registration.
- **Canonical URL:** https://ekas.io/rules/10dlc/operational/ops-142/

## Why this rule exists

Sharing is permitted only where it can be unpicked, and the register is what unpicks it: a complaint about one message has to resolve to one sender within the time a carrier gives you, which is short. Without it a shared arrangement is indistinguishable from the sub-aggregation the previous rule prohibits, and it will be treated as such.

## How to fix it

Keep a current list of every sender on the shared number, with the approval that permits the arrangement, somewhere you can produce it the same day. Done when a message can be attributed to a sender without asking anybody.

## Check this yourself

**If a number you send from is shared, was the arrangement approved — and could you attribute one message to one sender the same day?**

1. Confirm the sharing arrangement was approved in the first place. An undocumented one is a different and worse finding.
2. Keep a current list of every sender on the number, with the approval that permits it, where you can produce it same-day.
3. Test it: pick a message and attribute it without asking anybody.

*What wrong looks like:* A complaint has to resolve to one sender inside the short window a carrier gives you. Without the register, a permitted shared arrangement is indistinguishable from prohibited sub-aggregation and gets treated as such.

## Notes

A register inside the operator, and no registration field even says the number is shared. What the user has to confirm is that the sharing arrangement was approved in the first place — an undocumented one is OPS-141, not this rule.