You buy a list of 40,000 "mobile" contacts. You load it, register your campaign, and blast. Roughly a third of those numbers never had a chance of receiving your text — they're landlines and non-textable VoIP lines. You paid a segment for each anyway, your delivery rate looks broken, and you've quietly texted numbers you have no consent basis to touch.
Full disclosure: I work for Ready, an SMS platform. So I have a bias toward "clean your list before you send." But the line-type problem isn't a Ready thing — it's a fact of how phone numbers get sold, aged, and reassigned. This post is about the scrub that happens before DNC and litigator checks: figuring out what kind of number you're even holding.
What "line type" actually means
Every phone number in North America maps to a carrier and a technology. Screening tools resolve that into three buckets:
- Wireless — a mobile handset. This is the only line type SMS reliably reaches.
- Landline — a copper or fiber home/business line. Texting it does nothing; the message dies at the carrier.
- VoIP — a virtual number (Google Voice, RingCentral, softphones). Some accept SMS, many don't, and the routing is unpredictable.
The reason this matters more than it used to: number portability. People move their landline number to a cell, or their cell to a VoIP app, all the time. A list labeled "mobile" at the point of sale can be 20–35% not-actually-mobile by the time you send — rough industry range, not a hard stat, but I've watched purchased lists land in exactly that zone.
Why texting a landline is worse than wasting a segment
Start with the money, because it's the least scary part.
Say you've got 40,000 contacts and 30% are non-textable. That's 12,000 dead sends. A one-segment promo on Ready Standard is $0.02 + $0.0045 carrier = $0.0245 each. So:
`` 12,000 dead sends × $0.0245 = $294 wasted per blast ``
Send that campaign twice a month and you're lighting ~$588/mo on numbers that were never going to reply. Not catastrophic — but it's pure waste, and it compounds every send.
The bigger cost is invisible: deliverability reputation. Carriers watch your delivery-to-failure ratio. A campaign where 30% of messages bounce at the carrier looks like spam behavior, and that can throttle the good 70% of your sends. You registered 10DLC to get clean routing — and campaign use-case mismatches already cost you throughput; a garbage line-type ratio piles on top of that.
The liability angle: reassigned and mistyped numbers
Here's where it stops being a spend problem. TCPA exposure runs $500–$1,500 per text or call. Two ways line-type errors put you there:
- A wireless number you have no consent for. If your list mislabels a landline as mobile and you had consent (or a scrub) tuned only to landlines, you can end up texting a cell you never had permission to reach.
- Reassigned numbers. A number that was a consenting customer's cell 14 months ago may now belong to a stranger — who never opted in and may be a serial complainer. Line-type screening won't catch reassignment on its own, but it's the same layer of hygiene, and a 12-month-old list is roughly 30% reassigned or disconnected.
Line-type screening is the first filter. It doesn't replace DNC or litigator checks — it runs before them, so you're not paying to scrub numbers you can't legally use anyway.
Where line-type fits in the scrub order
Think of it as a funnel. Each stage removes numbers so the next stage costs less and the send is cleaner:
| Stage | What it removes | Why it goes here |
|---|---|---|
| 1. Line-type | Landlines, non-textable VoIP | Cheapest to drop first; no point scrubbing numbers you can't reach |
| 2. DNC | Federal + internal do-not-call numbers | Regulators check your internal list first |
| 3. Litigator / DNC-complainer | Known TCPA plaintiffs and serial complainers | A number can pass DNC and still sue you |
| 4. Consent check | Anyone without a valid opt-in record | Final gate before send |
That order matters. If you scrub litigators before line-type, you're paying to check numbers that were never going to receive your text. Doing line-type first shrinks the list you pass to every downstream stage.
And these are genuinely three different lists — people confuse them constantly. If that's new to you, DNC vs. litigator vs. TCPA lists is worth ten minutes, because passing one doesn't clear you on the others. (The short version: a number can pass DNC and still sue you.)
The scrub math on a real list
Let's run 40,000 contacts through the funnel with round-but-realistic hit rates for a purchased list.
Ready's TCPA & DNC litigator scrub is $0.005 per contact. Line-type identification is part of the same hygiene step. Here's how the spend stacks when you scrub in the right order:
`` Start: 40,000 contacts After line-type (–30%): 28,000 textable After DNC (–8%): 25,760 After litigator (–2%): 25,245 sendable ``
Now compare two approaches:
Scrub everything, send to what survives: `` Scrub 40,000 × $0.005 = $200 Send 25,245 × $0.0245 = $618 Total = $818 ``
No scrub, send to the whole list: `` Send 40,000 × $0.0245 = $980 ``
You spent less by scrubbing ($818 vs $980), reached the same real audience, protected your delivery reputation, and dropped the litigators and DNC numbers that carry the $500–$1,500 exposure. The scrub paid for itself before you count a single avoided complaint.
You only pay for what you scrub, so there's no minimum to make the math work. On a small list it's a rounding error; on a 40,000-contact purchased list it's the difference between a clean send and a throttled one.
When line-type screening isn't worth it
Honesty first: if you grew your list yourself through a keyword opt-in or a checkout SMS checkbox, your line-type problem is close to zero. People who text a keyword from their phone are, by definition, on a wireless number. Scrubbing a fresh first-party opt-in list for line type is mostly wasted effort.
Line-type screening earns its keep when:
- You bought or rented the list (rented data is a TCPA time bomb for other reasons too).
- The list is aged — anything past 6–12 months has drifted.
- You're mixing voice and SMS outreach, where dialing a reassigned mobile is its own liability.
That last one is where the Power Dialer and scrubbing pair up. Line-type also tells your dialer which numbers are worth a call versus a text, so you're not burning agent minutes dialing dead lines.
Re-scrubbing, because line type isn't permanent
A number's line type can change. Ports happen. Disconnects happen. A scrub is a snapshot, not a permanent stamp — Ready's litigator/DNC scrub results expire on a rolling basis, and line type drifts on the same clock. The higher your list's source risk, the faster it decays.
The practical rule: match your re-scrub cadence to how the list was sourced. Purchased lists need scrubbing roughly 3x as often as ones you grew. Line type is part of that same refresh — not a separate calendar to track.
The practical takeaway
Line-type screening is the cheapest, earliest filter in your compliance funnel, and it does two jobs at once: it stops you paying segments for numbers that can't receive them, and it keeps your carrier delivery ratio healthy so the good sends land. Run it before DNC and litigator checks, not after, so every downstream stage costs less.
If you're sitting on a bought or aged list, the order is: line-type → DNC → litigator → consent, then send. Ready runs the scrub at $0.005/contact, itemized so you can see exactly what you paid to clean versus what you paid to send.
You don't need to overhaul anything to try it — scrub a list and see the split before your next blast. Worst case, you learn your list was cleaner than you feared. More likely, you find the third you were about to text into a wall.