Know Your Upstream: How Carrier Enforcement Can Block Your Calls

The FCC continues to crack down on carriers that don’t follow the rules, and the effects ripple through the entire telecom ecosystem. If your calls are routed through a non-compliant provider, they can be blocked or flagged, even if your own practices are spotless. That’s why it pays to know your upstream providers. Otherwise, you may find your calls simply stop reaching customers.

The FCC’s crackdown on carriers

The FCC is mainly targeting voice service providers that fail to follow rules designed to prevent illegal robocalls, and it has several tools to enforce compliance.

A provider cut off from the network

In one widely reported case, the industry’s traceback group began investigating a voice service provider in 2024. The FCC found evidence that the provider was likely allowing illegal traffic through its gateway and ordered all voice service and intermediate providers to block its calls, effectively cutting it off from the US phone network. Downstream providers were given 30 days to comply.

The role of the Robocall Mitigation Database

The FCC also removed that provider from the Robocall Mitigation Database (RMD). To be listed, providers must show they’ve taken steps to comply with FCC robocall rules, and non-compliant companies can face fines of up to $10,000 per violation. Removal makes it extremely hard for a provider to work with anyone else. It isn’t a perfect system, but it helps regulators and the industry identify bad actors.

Upstream and downstream: the three provider tiers

Tier 1 (upstream)

The large carriers that own the core infrastructure, fiber networks and facilities, such as AT&T, Verizon and T-Mobile. They provide essential services to everyone downstream.

Tier 2 (downstream, hybrid)

Providers that rent bandwidth from Tier 1 carriers but also own some infrastructure, such as large cable companies. Others often choose them for their peering arrangements and lower costs.

Tier 3 (downstream, last mile)

Providers that handle the "last mile" to customers, including mobile virtual network operators and many smaller, lesser-known companies. They rely on Tier 1 and Tier 2 infrastructure, though some own local equipment. Tier 2 and Tier 3 providers can suffer local outages, and a Tier 1 outage can leave them unable to serve customers at all.

What removal from the RMD means

The FCC can fine providers that fall short of RMD requirements without removing them. Full removal usually follows a pattern of behaviour that lets scammers reach consumers. Once removed, a provider is effectively disconnected: US providers must stop carrying its calls until it complies and is reinstated. Providers that keep carrying its traffic risk:

• Cease-and-desist letters requiring them to block the banned provider within days.
• Network isolation, cutting them off from carrying calls.
• Substantial fines, and in extreme cases government action to halt operations.

Why knowing your upstream matters

The calling ecosystem includes many companies at different levels, and a single bad actor in your call path can make it hard to reach customers, clients and leads. Working with reputable providers helps, but it’s difficult to see every company your calls pass through. That’s why objective data about your own numbers is so valuable: it shows when something has changed, even if the cause is outside your business.

How to protect your calls

1. Ask each provider to confirm its RMD status and compliance program.
2. Map which numbers and campaigns run through which providers.
3. Use phone number monitoring to see quickly when numbers are flagged or labelled.
4. Confirm full A-level attestation with an attestation tester.
5. Have a backup route ready if a provider runs into trouble.

This article is general information, not legal advice. Telecom rules change often, so confirm current requirements with your voice provider and a qualified attorney.

Signs the problem is upstream

When answer rates fall, it’s natural to blame your own numbers. But some patterns point to a provider issue instead:

• Every number on one provider drops at the same time.
• Numbers on other providers carry on as normal.
• Monitoring shows no new labels on the affected numbers.
• Calls fail outright or never ring, rather than showing warnings.

If you see these signs, contact your provider straight away and be ready to move traffic.

Questions to ask a new provider

1. Are you listed in the Robocall Mitigation Database, and is your filing current?
2. Which upstream carriers do you use?
3. How do you verify your own customers?
4. Can you sign our calls with A attestation?
5. How will you notify us if your status changes?

Building resilience

For businesses that depend heavily on outbound calls, a single point of failure is a real risk. Keeping a second provider ready, knowing which numbers run through each route and monitoring answer rates per route means a provider problem becomes a quick switch rather than a lost week.

Frequently asked questions

Can my calls be blocked because of another company?

Yes. If a provider in your call path is cut off, calls routed through it can fail or be blocked.

How do I know which providers carry my calls?

Ask your primary provider about its upstream and downstream partners, and keep your own map of routes.

What is the Robocall Mitigation Database?

An FCC database where providers certify the steps they take to prevent illegal robocalls.