A plumber answering service is a phone line that picks up the calls your shop cannot — after hours, on a busy signal, on no answer — works out what kind of job it is, and decides whether to wake somebody. The deciding is the whole product. Every vendor in this category will tell you they “escalate true emergencies”; almost none of them will show you the table that does it.
This is that table. 18 rules, 9 of them set to wake the on-call tech, 7 to wait until morning and 2 to go on the calendar. It is the table shipped in the code, printed here by the build, and it is where sump pump failed and water is rising sits on the row that wakes somebody while sump pump failed, floor still dry sits on the row that waits.
On Call Bell has not answered a phone call yet. The safety gate, the triage rules, the call flow and the evidence trail are written and tested offline; the telephony is the next piece of work. Nothing on this page describes how fast or how reliably a live line answers, because no live line exists to measure. There is nothing to sign up for and no demo number. Everything below is either a decided price or a number you can count in the code.
There are only four things any after-hours line can do with a call, and three of them are yours to define. It can wake somebody tonight. It can capture the job and hand it over first thing. It can put a request on the calendar. Or it can stop, refuse to book, and point the caller at 911.
The fourth is the only one an owner does not get a switch for. When a caller says gas, carbon monoxide, fire, sparks or someone hurt, the line does not book them, does not put them through, and does not check first. It says who it is, says it cannot help with this, tells them to hang up and call 911 — from outside, if they are indoors, which is what the CPSC says to do — and hangs up so the line is free.
The other three rows are data. An owner can move any of them. Whether no hot water is worth waking a tech for on a Tuesday in July is a business decision, and a vendor who has made it for you has made it wrong for somebody.
The mechanism underneath is deterministic and runs before any model sees the call: rules first, and a model may only ever raise a tier, never lower one. There is no code path by which an interpretation of vague words talks the line out of waking you. A de-escalation can only come from a rule you wrote — water off and contained is first thing — and every call records which rules matched and which table version they came from.
Parsed out of the source at build time, so a row that changes tier in the code changes tier here. Tonight rings the on-call phone and waits for a keypress before connecting the caller; first thing captures the job and tells the caller who will text them and by when; scheduled reads the job back and puts an unconfirmed request on the calendar.
| Rule | Situation | Shipped tier |
|---|---|---|
| R01 | Sewage backing up into the home | Tonight |
| R02 | Whole-house or main line backing up | Tonight |
| R03 | Active leak, shutoff not found or not done | Tonight |
| R04 | Active leak that is spreading | Tonight |
| R05 | Burst pipe | Tonight |
| R06 | Sump pump failed and water is rising | Tonight |
| R07 | Water heater dumping onto the floor | Tonight |
| R08 | No heat during a cold snap (hydronic only) | Tonight |
| R09 | Leak, water off and contained | First thing |
| R10 | One fixture blocked, the rest fine | First thing |
| R11 | No water in the house | First thing |
| R12 | No hot water | First thing |
| R13 | Pipe frozen but not burst | First thing |
| R14 | Sump pump failed, floor still dry | First thing |
| R15 | Pilot out on a gas appliance, safety question answered no | First thing |
| R16 | Dripping fixture, running toilet, low pressure | Scheduled |
| R17 | Replacement, remodel, estimate or maintenance | Scheduled |
| R18 | Commercial property with a backup or no water | Tonight |
Two rows are conditional on switches an owner sets. R08 only fires for shops that service boilers and hydronic heat, and only while cold-snap mode is on. R18 only fires for shops that take commercial work. A shop that does neither never sees either row.
One row is only reachable at all after the safety gate has cleared the call. R15 — pilot out on a gas appliance — is a first-thing row, but only once a safety question has been answered no. That ordering exists because the symptoms a caller offers instead of a gas smell are, in the CDC's own words, often “flu-like” — its own list is headache, dizziness, weakness, upset stomach, vomiting, chest pain and confusion. No triage tier is the right answer to that sentence; the stop is.
Every fact the line extracts from a call is tri-state: true, false, or nobody asked. That third state is the one that separates a rule table from a keyword filter, and it is a one-line rule with an expensive consequence.
R03 is active leak, shutoff not found or not done — a tonight row. It fires when the water is running and the shutoff is not known to be done. If nobody asked whether the water was off, the rule fires. It does not get to assume the good case because the question never came up.
The mirror image is R09, leak, water off and contained, which is a first-thing row and needs both facts positively established before it will let the call wait until morning. A shop that reads its own call log will find calls that woke somebody because a question was skipped. That is the designed direction of the error.
Three modifiers can push a matched rule up one tier: vulnerable occupants in the house, cold-snap mode, and a multi-unit building. Each can be switched off by the owner, and a modifier alone is never a dispatch reason — it only applies once a rule has already matched. The four-outcome model these sit inside is written out in full on the page for contractors and other trades.
An AI receptionist for plumbers is the same product under a friendlier noun, and the noun is doing work. A receptionist is a person who exercises judgement. What is actually shipping in this category is a language model plus a script, and the difference shows up exactly once: on the call where somebody is hurt and the caller is understating it.
So the design here puts the model last, not first. A fixed word list runs before the model gets the call, and if that list fires, the call ends in a referral to 911 and the model never sees it. The model can raise a tier and can never lower one. There is no setting that turns the word list off — not a default, not a toggle in an account page; it does not exist in the code.
A word list can be beaten by words, and this one is: 43 of 374 adversarial sentences still pass it in silence, and every one of them is printed on the miss ledger. Asked directly whether it is a person, the line says it is an AI, every time, and that is not switchable either.
Independent plumbing companies running one to three trucks, in the US. Not a franchise, not a 40-truck operation with a dispatch desk, and nowhere outside the US — the name this is being built under is cleared for one market and no other.
The line never touches your main number during the day. It sits behind it on three conditions and no others: you are on the other line, nobody answers, or you have gone home. That is a narrower product than a 24/7 outsourced switchboard, deliberately, and it is why the price works out the way it does on the cost comparison.
Not on this table. Of the 18 shipped rules, 9 are set to ring the on-call phone tonight, 7 capture the job and wait until morning, and 2 go on the calendar as an unconfirmed request. Every row except the safety stop is data an owner can move.
The line does not book it, does not transfer it and does not ask a clarifying question first. It says who it is, says it cannot help with this, tells the caller to hang up and call 911 from outside if they are indoors, says nobody is being sent, and hangs up so their line is free. There is no setting that turns this off.
Yes, for every row except the safety stop, which is read-only. Predicates are code and tiers are data: you can change what a situation is worth, but not what the situation is. Every call records the rule table version it ran against, so a change is auditable after the fact.
No. On Call Bell has not answered a phone call yet, there is no demo number, and there is nothing to sign up for. What exists is the code and 511 offline tests behind the safety gate. Write to hello@oncallbell.com if you want to be told when a real number exists.
If you run a shop and something on this page is wrong — a rule that would wake you for nothing, a phrase the word list should catch and does not — write to hello@oncallbell.com. A person reads it. That is more useful to us than a signup, and there is no signup yet anyway.
Last checked against the code on 2026-09-06