Line type is the kind of service a phone number was allocated for. Spaw answers one of mobile, fixed_line, fixed_line_or_mobile, voip, toll_free, premium_rate, shared_cost, personal_number, pager, uan, voicemail or unknown.
What Spaw answers
line_type carries the value and line_type_source says which dataset decided it: numbering_plan when the numbering plan decided it (the metadata for the prefix, or the regulator's plan where it types a range differently, as for Ofcom's drama ranges and the UK 084 and 087 ranges below), block_allocation when a North American fixed_line_or_mobile was settled by looking up who holds the block.
In the United Kingdom, 084 and 087 numbers answer shared_cost, not premium_rate. Ofcom's numbering plan (the version of 22 April 2025) designates 0843 to 0845 and 0870 to 0873 as non-geographic numbers whose service charge is capped, at 5.833p and 10.83p a minute or a call before VAT, and keeps premium rate for the 09 range, capped at 300p a minute. The numbering metadata types those two ranges as premium rate, so Spaw reads them the way the plan does. Ofcom's premium-rate-services rules still cover 0871 to 0873, so a sender that treats those as premium rate should block shared_cost as well.
Which line types a country's plan uses, with an example number of each, is on its page under phone facts by country; the United Kingdom is one.
Four line types carry weight on the phone risk score: premium rate +60, VoIP +30, pager +30 and shared cost +20. The reasoning is about who pays and who can be reached, not about the technology being worse.
Toll-free, premium rate, shared cost and personal numbers
Four types describe who pays for a call, or where it is sent, rather than the network behind the number, and the numbering plan always decides them (line_type_source: numbering_plan). A toll_free number is free to the caller: 800, 833, 844, 855, 866, 877 and 888 in the North American plan, and 080 in the United Kingdom, a range Ofcom's plan marks "Free to caller". A premium_rate number charges the caller for a service on top of the call: 900 in North America, 09 in the United Kingdom. A shared_cost number splits the charge, as the UK's 084 and 087 above do. A personal_number follows its holder: Ofcom's plan designates 070 for Personal Numbers, a number-translation service that lets someone be called at one number and take the call "at almost any Telephone Number, including a Mobile Number", and the metadata types several North American 5XX codes, 500 among them, the same way. In libphonenumber 9.0.37's metadata, 184 of the 245 regions have a toll-free range, 150 a premium-rate range, 59 a personal-number range and 53 a shared-cost range.
Premium rate is the only one of the four the default SMS policy blocks, through its premium_rate signal. toll_free and personal_number carry no risk weight, and an account that never sends to them can list them, like any type but fixed_line_or_mobile, in blocked_line_types.
What it is not
Line type is not a claim that the handset is reachable today, and it is not port-aware — it describes the allocation. fixed_line_or_mobile is a real answer, not a failure: in the North American plan the two share blocks, and when the block holder settles nothing the honest answer is that both remain possible.