An SMS-receiving number, often called a disposable or temporary phone number, is a number that a public website publishes so that anyone can read the text messages sent to it. A verification code sent there can be read by whoever opens the page, so the number proves nothing about the person who typed it.
What Spaw answers
Spaw merges two open lists of such numbers, from iP.1 Networks and Castle (both MIT), every day. is_disposable is true when the merged table holds the number, whether a list carries it today or every list has dropped it and it was last seen within the last 730 days, and disposable_seen_at gives the date it was last seen. Three signals follow from the listing:
| Signal | When | Weight |
|---|---|---|
disposable |
Listed and seen within the last 365 days (an undated listing counts as fresh), or dropped by every list and seen within the last 90 days | +70 |
disposable_stale |
Listed or dropped, but not seen inside those windows; a dropped number is kept at its last-seen date for 730 days | +40 |
disposable_range |
Not listed itself, but in a 1,000-number range holding 10 or more listings that still score disposable; is_disposable stays false |
+30 |
disposable is one of the default block signals of the SMS policy, so a fresh listing answers ok_to_send: false with blocked_by: "disposable". The other two pass the defaults on their own, because +40 and +30 are within the ceiling of 60. The test numbers show both ends: +1 202 555 0103 answers is_disposable: true, a score of 70 and blocked_by: "disposable"; +1 202 555 0113 answers disposable_range, a score of 30 and ok_to_send: true.
What the lists hold
The two lists synced on 24 September 2026 held 128,030 numbers under 103 calling codes. North American numbers were the largest group, 35,988 (28.1%), followed by +44 with 15,877 (12.4%) and +86 with 13,130 (10.3%). Most listings are old: on 27 September 2026, 18,934 of them (14.8%) were fresh enough to score disposable, and the rest scored disposable_stale. Of the 25,659 listed numbers with a US area code, at least 64.7% sit in blocks whose holders are on Spaw's classification list of virtual-number wholesalers and VoIP providers (the holder the block was allocated to, not who serves the number today), against at least 19.7% of all allocated US numbers in NANPA's tables of 26 September 2026. The full table by calling code is on the phone statistics page.
What it does not mean
A listing says a website published the number on a date. It says nothing about who holds the number today: the sites give numbers up, and a carrier can issue one to a subscriber who never saw the site, which is why the weight drops once a listing is stale.
is_disposable: false means not listed, not safe. Many SMS-receiving numbers are never scraped into a list; disposable_range covers only the unlisted neighbours of listed numbers, and a real subscriber can hold a number beside a run of rented ones.
The lists name no owner and neither does Spaw: there is no reverse lookup and no caller name in any answer.