What is line type?
Line type is the category a phone number belongs to, such as mobile, landline, VoIP or toll-free, which affects how it can be called.
Why it matters for sales teams
Line type tells a rep what to expect. A mobile number usually reaches one person. A landline may be a desk phone or a shared office line. A VoIP number could be either.
It also matters for compliance. The TCPA treats calls made with an autodialer or an artificial or prerecorded voice differently depending on whether the number is assigned to a cellular service or is a residential line. Numbers can be ported from one kind of service to another, so the line type a number started with may not be the one it has today.
Example
A list has two numbers for the same prospect. A phone number validation check shows one is a mobile line and the other a landline at the company's office. The rep knows which one is more likely to reach the person directly.
Line type vs phone carrier
Line type is what kind of service a number uses. The phone carrier is the company providing that service. Both can change when a number is ported.
This is a general definition, not legal advice.