The circuit acceptance test: proving a new circuit before you sign for it
The check a business runs on a newly delivered circuit before accepting it, on its own measurement, to confirm the circuit performs as contracted rather than merely showing connected.
A circuit acceptance test is the check a business runs on a newly delivered network circuit before accepting it, to confirm the circuit performs as contracted rather than merely showing as connected. Run on the customer's own measurement over a few days, it turns "the link is up" into evidence that the circuit can carry the work.
What a circuit acceptance test is
When a carrier delivers a new circuit, the standard hand over is a light: the link is provisioned, it passes a basic reachability check, and the customer is asked to sign. A circuit acceptance test replaces that moment of trust with a measured one. It runs the circuit through the conditions it will actually meet in production, records how it behaves, and produces evidence that can be kept, compared against the contract, and referred back to if the circuit later underperforms.
Why “it’s live” is not the same as “it’s right”
A circuit can be provisioned correctly and still fail to deliver what was bought. Throughput can fall short under real load. Latency and packet loss can sit inside tolerance at hand over and drift outside it in week three. A fault that only appears at a busy hour is invisible to a five minute check. Accepting on the carrier’s word means accepting all of that risk unseen, and discovering it later as a support ticket rather than a contractual point at sign off, when the leverage has already passed. Reported as a monthly average, the shortfall becomes the familiar watermelon SLA: green on the report, red in use.
What good acceptance evidence looks like
Strong acceptance evidence has three properties:
- Continuous rather than a snapshot, so it captures the bad hour and not just the calm one.
- Measured at the level of the applications that matter, not only the interface, so it reflects the work the circuit exists to carry.
- Independent, held by the customer rather than supplied solely by the party being tested, so it can be reconciled against the carrier’s own report.
A defensible acceptance report records throughput, latency, packet loss and application performance across the test window, with the times and conditions attached.
The cost of skipping it
The cost lands twice. First as an acceptance dispute: a circuit signed for on trust is hard to challenge later, because there is no baseline to point to. Second as field cost. Industry estimates put a single truck roll at roughly $150 to $500, with the true loaded cost often approaching $1,000 once indirect time is counted, and a meaningful share of those are “no fault found” dispatches, where an engineer is sent to a problem the data could have located or ruled out. A measured acceptance test at the start prevents both the argument and many of the visits.
How to run one
The practical version is simple. Before sign off, leave a measurement on the circuit for one to five days. Test the specific applications the site depends on, not a generic list. Capture performance continuously across the window, including the busy periods. Keep the resulting record independently, so it is yours to reconcile against the carrier. Accept the circuit on that evidence, or take the same evidence back to the carrier when it shows the circuit is not delivering what was contracted.
How XVOLV does it
Link is built for exactly this. Left on a new or troubled wireline circuit for one to five days, it runs a continuous diagnostic and application test suite and produces a provisioning report you can use two ways: as the evidence behind accepting the circuit on your own measurement, or as a defensible record to take back to the carrier when the circuit falls short. Parallax then turns measured performance into deterministic reports and service credits, so the argument is settled on the record. The reasoning is set out in the white papers The Accountable Line and Proof by Rule.
Frequently asked questions
What is a circuit acceptance test?
A circuit acceptance test is a check run on a newly delivered network circuit before it is accepted, to confirm it performs as contracted rather than simply showing as connected. It is strongest when run continuously over several days on the customer’s own measurement.
Why isn't "the circuit is live" enough?
Because a circuit can be provisioned correctly and still underperform. Throughput can fall short under load, and intermittent faults can appear days after hand over. A brief reachability check at delivery cannot see any of that, so accepting on it carries the risk unseen.
How long should an acceptance test run?
Long enough to capture real conditions, including busy periods. A window of one to five days of continuous measurement is usually enough to expose intermittent loss, congestion and variability that a single point in time test would miss.
What should a circuit acceptance report contain?
Throughput, latency and packet loss measured across the test window, application level performance for the services the site actually uses, and the times and conditions those figures were recorded under, held independently so they can be reconciled against the carrier’s own report.
What is a "no fault found" dispatch, and how does acceptance testing reduce it?
A “no fault found” dispatch is a field visit where the engineer finds nothing wrong, often because the fault was intermittent or misdiagnosed. Continuous measurement locates or rules out the problem before a truck is sent, cutting both wasted visits and their cost, estimated in the industry at up to around $1,000 each.
Sources
- Industry estimates of truck roll cost ($150 to $500 typical, up to ~$1,000 loaded; includes "no fault found" dispatches), as summarised by field service and telecoms operations analyses. asentria.com
- MEF — carrier Ethernet service and performance standards. mef.net
- TM Forum, SLA Management Handbook (GB917). tmforum.org