The best ignition interlock provider is the one that covers your city
You will visit a service center every 30 to 60 days for the length of your term. A provider with a cheaper monthly fee and no center within an hour of you is not the cheaper option. Start with coverage, then compare cost.
| Provider | States | Centers | Cities | Only choice in | Publishes a price |
|---|---|---|---|---|---|
| Smart Start | 49 | 2,604 | 1,628 | 278 cities | no |
| LifeSafer | 49 | 2,203 | 1,741 | 450 cities | $70–$150 |
| Intoxalock | 48 | 5,927 | 3,836 | 1,938 cities | $54.99 |
| RoadGuard Interlock | 35 | 799 | 647 | 80 cities | no |
| Low Cost Interlock | 31 | 1,250 | 952 | 70 cities | no |
| ADS Interlock | 28 | 502 | 451 | 53 cities | no |
| Guardian Interlock | 10 | 207 | 180 | 5 cities | no |
The cheapest interlock device, honestly
There is no single cheapest provider nationally, and any page claiming one is guessing. Thirteen states cap or publish what a device may cost, and inside those states the price is largely fixed whoever you pick — Virginia caps the monthly fee, and no provider undercuts a cap. Everywhere else the quote depends on your state and the center doing the work.
The cheapest option near you is therefore a local question, not a brand one. What reliably changes the total is the length of your term and the drive to calibration, not the sticker price: two extra months of monitoring costs more than the difference between the cheapest and dearest installation. How the full-term cost adds up →
The smallest and most discreet device
All certified devices are built to the same federal specification, so the handset is roughly the size of a mobile phone in every case, connected by a cable to a control box hidden under the dashboard. Nobody outside the car sees it, and a passenger sees a handset in a cup holder.
The real difference in visibility is the camera. Several states require one that photographs whoever is blowing, and where the state requires it no provider can offer you a version without it. What the device actually is →
What the public record says about each company
An interlock provider is a company you will be tied to for months, and it bills you monthly. That makes its conduct part of the choice, and it is the part no vendor page covers. Below is what regulators and courts have said, with the docket or the order behind each line. A case is not a verdict on the company, and several ended in the company’s favour — the outcome column says which.
| Provider | Year | What was alleged | Outcome |
|---|---|---|---|
| Smart Start | 2021 | Lease disclosures said to be missing from the service agreement source | The court dismissed the complaint with prejudice on 12 March 2021, and denied reconsideration on 8 April 2021. The claims did not succeed. |
| Smart Start | 2017 | The company sued the state over real-time location reporting source | The court blocked the retrofit deadline in December 2016, sparing roughly 3,000 existing devices, and extended the order on 16 February 2017 to new enrollees. The legislature later prohibited location tracking in the program without a court order. |
| LifeSafer | 2020 | The same lease-disclosure claim, brought in another state source | The case terminated on 16 January 2020. In June 2020 the court awarded the plaintiff $2,000 in fees and $455 in costs. |
| LifeSafer | 2019 | Lease disclosures said to be missing from the program service agreement source | Settled. A fund of $36,819 was created for 8,182 class members, working out at roughly $22 to $45 each, and the company agreed to change its form service agreement. Settlement is not an admission of liability. |
| Intoxalock | 2025 | Sales calls recorded without consent source | A settlement fund of $1,747,500 received final approval on 3 March 2025, with individual payments capped at $5,000. A settlement resolves the case without any finding of liability, and the company did not admit the claims. |
| Intoxalock | 2024 | Calls that continued after do-not-call requests source | The court denied the company's motion to dismiss on 10 May 2024, so the case proceeds. Nothing has been decided on the merits: at this stage these remain the plaintiff's allegations. |
| Intoxalock | 2023 | Mailings that looked like court documents source | The company rewrote the mailer — removing the instruction to call about "regaining your driver's license" and reformatting it so it no longer resembled a court document — and the Attorney General closed the investigation on 5 May 2023, seven weeks after the letter. |
| Intoxalock | 2018 | Location data collected by modem-equipped devices source | The court rejected those claims in an unpublished decision of 17 December 2018, which in Minnesota carries limited precedential weight. Separately, and while the case was running, the legislature amended the law so that program guidelines may not require manufacturers to collect location data at all. |
| Guardian Interlock | 2016 | Whether a statutory fee cap caps the whole bill source | The company won. On 23 February 2016 the court held that the $25 cap covers maintenance only, and does not limit rental, tax or damage-waiver charges. The practical lesson runs well beyond Oklahoma: a capped fee is not a capped bill, and the cap you read about may cover one line of several. |
| Guardian Interlock | 2015 | Decertification by the state, and the company's suit over it source | Reported at the time as a pending suit for damages and a restraining order. We have not found a published decision, and record this as the dispute it was rather than as an outcome. |
Which interlock is easiest to use
Every certified device is built to the same federal specification, so the blowing pattern, the warm-up and the rolling retest work the same way whoever supplies it. What actually differs is three things, and none of them is the handset.
The first is the camera. Where the state requires one, no provider can hand you a version without it, and where the state does not, some still fit it. The second is how the data reaches the agency: some report over the air, others only at the calibration visit, and that decides whether a mistake is on your record before you can explain it. The third is the service network, which decides how far you drive every 30 to 60 days for the rest of your term. How the device works →
Is one provider better than another
The pairings people search for — LifeSafer against Intoxalock, Intoxalock against Smart Start — have no national answer, because the two variables that decide the outcome are local. Whether the brand has a center in your city, and whether your state caps the fee, matter more than anything on either company’s website. In a capped state the price is the same whoever you pick; in an uncapped one the same brand quotes differently in two cities.
There is also a case where the question does not arise at all: if your paperwork names a manufacturer, that is the manufacturer, and switching mid-term means paying a second installation. The three pairings, side by side →
Questions people ask before choosing
Which ignition interlock is the best?
There is no national answer, and a page that names one is selling something. Every certified device meets the same federal specification, so the hardware is not the variable. The variables are local: whether the brand has a service center close enough that a calibration every 30 to 60 days is not a half-day trip, and whether your state caps the fee. In a capped state the price is effectively the same whoever you pick. Where your court order or licence paperwork names a manufacturer, there is no choice to make at all.
Is LifeSafer better than Intoxalock?
They are the two largest networks, and which one is better is a question about your city rather than the companies. Check the two numbers that matter where you live: how many centers each has within a reasonable drive, and whether your state publishes a fee cap. Both have entries in the public record — the table above lists them with the docket behind each — and neither record makes one obviously safer than the other.
Is Intoxalock or Smart Start better?
Intoxalock runs the larger network by service-center count; Smart Start is approved in a comparable number of states and is often the one operating where smaller networks are absent. Again the decision is local: in cities where only one of them has a center, the comparison is over. Where both are present, the difference in the monthly bill is usually smaller than the difference in the drive.
Do cops know if you have an interlock device?
Yes, before they reach your window. The restriction sits on your driving record, and several states print it on the licence itself — New York puts "interlock device" on the back of the document. Driving a vehicle without the device while restricted is its own offence: a class 1 misdemeanour in Arizona, and grounds to extend the requirement by a further year.
What is the most discreet interlock device?
All of them are about the size of a mobile phone, connected by a cable to a control box hidden under the dashboard, because the federal specification leaves little room to differ. Nothing is visible from outside the car. What changes visibility inside it is the camera: several states require one that photographs whoever blows, and where the state requires it no provider can supply a version without it.
How we rank
We rank on things we can count: how many states a provider operates in, and how many unique certified centers we can confirm. We do not rank on a star score, because we have not yet built a scoring method we could defend line by line.
When we publish confirmed pricing, full-term cost joins the ranking. Our editorial policy explains what we will and will not do here.