Line type is the most useful single field you can add to a purchased list, because it determines two separate things at once: whether a message can physically arrive, and how much legal risk the number carries.
The line types you will see
| Line type | Receives SMS | Notes for outbound |
|---|---|---|
| Mobile | Yes | Reachable by call and text, but carries the strictest TCPA consent rules. Verify consent and litigator status first. |
| Landline | No | Calls connect; texts fail silently. Remove before any SMS campaign. |
| VoIP | Sometimes | Internet-based. Cheap to create and discard, so concentrated in poor-quality lists. |
| Toll-free | Rarely | An 800/888/877 business line billed to the receiver. A company switchboard, not a consumer lead. |
| Disconnected | No | No longer in service. Wastes agent time and depresses connect rates. |
Why the number itself tells you nothing
Two mechanisms defeat any attempt to infer line type from the digits:
Prefix blocks are mixed. The North American Numbering Plan never reserved separate ranges for mobile and fixed lines the way some countries did. A given area code plus prefix can contain both.
Numbers move. Local number portability lets a subscriber carry a number between carriers and between service types. Any static lookup table built on prefix assignment is out of date the moment porting occurs — and porting is routine.
This is why free "area code lookup" tools cannot answer the question, and why carrier-level validation costs money: it queries live records rather than a cached table.
The compliance angle
The TCPA's strictest requirements attach to mobile numbers — marketing robocalls and robotexts to a mobile need prior express written consent. Knowing line type therefore tells you which consent standard applies to each row in your file.
It cuts both ways. Identifying mobiles tells you where your legal exposure is concentrated; identifying landlines and disconnected lines tells you where your spend is being wasted. A full scrub handles both alongside the do-not-call and litigator checks.
See it on a real number
The free phone number lookup returns line type, carrier and TCPA litigator status for any US number — 5 a day, no card required.
Frequently asked questions
Can you tell line type from the area code?
No. In the North American Numbering Plan, prefixes are not segregated by line type — the same 202 prefix block contains both mobiles and landlines. Local number portability compounds it: a number issued as a landline twenty years ago may be a mobile today. Only a carrier-level lookup reflects current reality.
Why does line type matter for SMS?
Landlines cannot receive SMS. A marketing text sent to one is typically billed to you and never delivered, and you usually get no bounce — so the spend disappears silently. Filtering to mobiles before a send is the single cheapest improvement to SMS economics.
Is VoIP bad?
Not inherently — plenty of legitimate businesses and individuals use VoIP. But VoIP numbers are cheap to create and discard, so they are over-represented in low-quality, recycled and fraudulent lead lists. Treat a high VoIP proportion as a signal about the list, not a verdict on the individual.
How do I check line type in bulk?
Upload a CSV to a bulk validator. NumberBroom appends line type, carrier and litigator status to every row at $0.044 per row. For a single number, the free lookup tool returns the same fields.