# OPS-139 — One number, one static route

> Each 10DLC, short code or toll-free number must use a single static route; dynamic routing is permitted only for major network outages.

- **Rule ID:** OPS-139
- **Layer:** Operational (`OPERATIONAL`)
- **Checks:** `route configuration per number`
- **Severity:** BLOCKING — Breaking this rule gets the submission rejected outright.
- **When it bites:** Falls due after approval, once you are live and sending
- **How it is detected:** Human check — only someone holding the document can settle it
- **Fix type:** Wait on an external system or a required interval
- **Required by:** T-Mobile, AT&T, Vonage, Telnyx
- **Applies:** Applies to every 10DLC registration.
- **Canonical URL:** https://ekas.io/rules/10dlc/operational/ops-139/

## Why this rule exists

Static routing is what makes traffic attributable — carriers trace a complaint back through the route, and a number whose path changes per message cannot be traced or trusted. Dynamic routing is also how grey routes get used without anybody choosing one, since a least-cost router will find them on its own.

## How to fix it

Pin each number to one authorised route and disable least-cost or failover routing except during a declared outage. Done when the path a message takes is the same one every time and you can name it.

## Check this yourself

**Is least-cost or failover routing enabled on your account — and can you name the single route each number takes?**

1. Ask your provider directly whether least-cost routing is on. It often is by default.
2. Pin each number to one authorised route and disable failover except during a declared outage.
3. Done when the path a message takes is the same one every time and you can name it.

*What wrong looks like:* A least-cost router finds a grey route on its own, so nobody chose one and the traffic is on it anyway. A number whose path changes per message cannot be traced back from a complaint.

## Notes

Carrier-side routing configuration. What the user has to ask their provider is whether least-cost routing is enabled on their account — it often is by default, and it is the mechanism behind the grey-route rule below.