Most organizations discover 10–20% of their telecom inventory is no longer serving an active location. Here's how to find it, and what to do about it.
What zombie services are, and why they survive
A zombie service is any circuit, line, device, or subscription that continues to be billed after the location it serves has closed, consolidated, or stopped using it. They're not the result of fraud. They're the result of operational gaps, specifically, the gap between the team that manages locations and the team that manages telecom.
When a location closes, someone notifies facilities. Someone notifies HR. Someone updates the org chart. But the person responsible for canceling the T1 circuit, the alarm line, the mobility devices, and the SaaS subscriptions tied to that address? Often, nobody. Not because anyone is careless because no one has a clear line of ownership across all of those systems simultaneously.
The result is services that keep running, invoices that keep arriving, and costs that keep accumulating, sometimes for years.
The numbers are worse than most finance teams expect
In our work across complex, multi-site environments, we consistently find that 10–20% of active inventory, meaning the services being billed and paid for right now, is no longer serving an active, productive use. Some of that is zombie locations. Some is service creep: lines added for a project that ended, devices assigned to employees who left, contracts that renewed for capacity no longer needed.
On a $10 million annual telecom spend, a 15% zombie rate is $1.5 million being paid for nothing. Not optimized inefficiently. Paid for nothing.
What makes this particularly striking is that these costs have usually been audited. They appear in reports. They've been reviewed by finance. They've passed through accounts payable dozens of times. The problem isn't that no one looked, it's that looking at invoices isn't the same as knowing whether the underlying services are still needed.
How zombie services hide in plain sight
There are three primary reasons zombie services survive audits:
Inventory is incomplete. Most organizations don't have a current, accurate record of what they're running at each location. They have billing data, which tells you what you're paying for, and they have location records, which tell you what sites are active. But reconciling those two lists, service by service, address by address, is manual, complex, and rarely done comprehensively.
Carrier billing doesn't reflect operational reality. When a location closes, the carrier doesn't automatically disconnect services. They continue billing until someone submits a disconnect request. If no one submits the request because the disconnect process wasn't part of the location-closing workflow, the services live on indefinitely.
No one owns the reconciliation. Finance owns the budget. IT owns the infrastructure. Operations owns the locations. TEM (if you have it) owns the invoices. But the question "is this service still needed at this address" sits at the intersection of all four, and without a single accountable owner, it falls through every time.
A systematic approach to finding them
The starting point is always inventory, not billing inventory, but physical inventory. What services are provisioned at each address, matched against whether that address is operationally active and whether each service type is still required there?
This reconciliation has to happen at the service level, not the account level. A carrier account serving 50 locations may have 10 active, 35 operating normally, and 5 where circuits are running to closed facilities, but the account-level view shows only that the invoices are being paid correctly against contract rates. The zombie services are invisible at that resolution.
Once you have a reconciled inventory, the process of identifying candidates for disconnect becomes structured: services at closed locations, services at active locations where the service type is no longer operationally justified, and services in a "gray area" that require a conversation with the location owner to confirm.
The disconnect process matters as much as the identification
Finding zombie services is only half the work. Disconnecting them without creating service disruptions or contract penalties is the other half, and it's where a lot of recovery efforts stall.
Carrier disconnect processes vary widely. Some require written notice 30 days in advance. Some have minimum contract terms that make early disconnection costly. Some have specific technical steps required before billing will stop. Getting all of this right requires knowing the contract terms, knowing the carrier process, and having someone who will actually manage the disconnect through to completion and confirm the credit.
Without that follow-through, zombie services often survive even after someone identifies them because the identification happened, but the disconnect process wasn't owned.
Preventing new zombies
The longer-term fix is building technology offboarding into your location lifecycle process. Every location close, every restructuring, every acquisition integration should trigger a formal technology review: what is provisioned here, what needs to be retained, what needs to be migrated, and what needs to be disconnected.
This doesn't have to be complex. It requires a checklist, a responsible owner, and a connection between your location management process and your technology governance process. Most organizations have both of those things, they just haven't been connected.
The organizations that do this well don't find zombie services in audits. They prevent them from being created in the first place.