Count your calls first. If nobody answers the phone in working hours, run the AI receptionist on every call. If the office answers most daytime calls and the gap is evenings and weekends, run it after hours. If the office only misses calls at busy moments, run it as overflow, forwarded when the line is busy or unanswered.
The choice matters more than the vendor, because most receptionist tools bill by volume, and the mode decides how much volume reaches them. In all-calls mode you pay per conversation for calls a person would have taken anyway. Overflow looks cheapest on paper, but it only works if your carrier's forwarding rules fire every time, so the phone settings deserve as much attention as the AI.
Three modes, and what each does to a call
Vendors treat partial cover as a normal way to start. Jobber's receptionist page describes switching it on for after hours, weekends or while you are on a job, with calls and texts controlled separately, and Rosie's pricing page lists the question "Can I start using Rosie for after-hours and overflow calls only?" in its FAQ. Each of those is a different job for the same tool.
| Mode | Who answers first | Best when | Main risk |
|---|---|---|---|
| All calls | The AI, every time | Nobody answers the phone in working hours, such as an owner on the tools | Paying per conversation for calls a person would have taken |
| After hours | The office in hours; the AI outside them | The office covers the day, and the gap is evenings, weekends and lunch | Schedule gaps: public holidays, early closing, staff leave |
| Overflow | The office first; the AI if the line is busy or unanswered | The office is staffed but swamped at certain times | Forwarding settings that misfire; callers waiting too long to hear anyone |
| After hours and overflow | The office in hours; the AI on overflow and outside hours | You have both gaps | Two rule sets to maintain and test |
Overflow is the one that needs the most care, because it depends on your phone provider's forwarding rules and not only on the AI tool. It is also the cheapest way to try the technology, because only the calls you would have missed ever reach it.
Count first: a two-week call log and five numbers
You do not need software to choose a mode. You need two weeks of your own call history, which your carrier's online account, your business phone system or even your mobile's call log can export. Delete caller names and keep date, time, direction, whether a person answered, and call length. Then ask ChatGPT or Claude to count:
This is two weeks of incoming calls to a plumbing firm's office line. Office hours are 8 a.m. to 5 p.m., Monday to Friday. Columns: date, time, answered_by_person (yes/no), duration_seconds.
Report, as a table:
1. Calls per week, split into in-hours and after-hours.
2. In-hours calls answered by a person, as a number and a percentage.
3. In-hours calls missed, grouped by hour of the day and day of the week, so I can see when they cluster.
4. After-hours calls per week and how many lasted over 60 seconds (likely real jobs).
5. Any phone number that called three or more times (likely regular or commercial customers).
Do not guess missing values. List any rows you could not classify.Check the totals yourself against the raw file with a filter, because chat tools sometimes miscount rows. Then you have five numbers. This is an illustrative result for a six-van firm with two people in the office:
| Measure | Result | What it tells you |
|---|---|---|
| Calls a week | 260: 215 in hours, 45 after hours | The after-hours share is about one call in six |
| In-hours calls answered by a person | 177 of 215 (82%) | The office copes most of the time |
| In-hours calls missed | 38 (18%): Monday 8 to 10 a.m.: 14; lunch hour: 11; Friday 3 to 5 p.m.: 6; other: 7 | Misses cluster at peaks, so this is a capacity gap |
| After-hours calls | 45: 9 emergencies, 36 routine or long enough to be real jobs | Worth covering, with a fast route for the emergencies |
| Repeat callers | 6 commercial accounts called three or more times | They should reach a person, so they need transfer rules |
Those five numbers answer the question before any pricing is discussed. A firm whose office answers 82% of daytime calls, misses them in three predictable windows, and gets 45 calls a week out of hours does not need the AI on every call. It needs overflow in the windows, and cover outside hours.
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Buy nowThresholds by call volume and office hours
These are my starting thresholds, not industry benchmarks. Set your own from your log, and revisit them after a month of real use.
| Your log says | Mode | Why |
|---|---|---|
| Nobody answers the office line in working hours (an owner on the tools, one or two vans) | All calls | Every unanswered ring is a job going to the next firm on the list |
| The office answers about 90% or more of in-hours calls, and there are five or more after-hours calls a week | After hours | The gap is the time of day, so cover only that |
| The office answers 75% to 90% of in-hours calls, and the misses cluster in two or three windows | Overflow, plus after hours if the row above is also true | The gap is capacity at peak times |
| The office misses more than about a quarter of in-hours calls across the whole day | All calls through the working day while you fix staffing | The problem is not peaks; there are not enough people on the phones |
| Fewer than about five after-hours calls a week, and in-hours calls are rarely missed | None yet: voicemail with an automatic text-back | The volume does not justify a monthly fee; review each quarter |
Treat lunch hours, public holidays, staff holidays and early finishes as after hours. They belong in the same schedule, and they are the gaps that are easiest to forget until a customer mentions them. If more than one in five of your after-hours calls are emergencies, the transfer setup in the burst-pipe section matters more than the monthly price.
A six-van firm: the same calls under four modes
Take the call log above and price each mode on Jobber's published add-on terms, which the help article gives as $29 a month including 30 conversations, then $0.79 for each extra one. Spam and conversations tagged "no conversation" do not count. At 4.33 weeks to a month, the arithmetic is:
| Mode | Calls a week reaching the AI | Conversations a month | Cost a month |
|---|---|---|---|
| All calls | 260 | 1,126 | $894.84 |
| After hours only | 45 | 195 | $159.35 |
| Overflow only (in-hours misses) | 38 | 165 | $135.65 |
| After hours and overflow | 83 | 359 | $288.91 |
For example, all calls is $29 plus 1,096 extra conversations at $0.79, which is $894.84. If the firm is on Jobber's Plus plan, which includes the receptionist with unlimited usage according to the same article, the cost is the same in every mode and the choice is purely about service. Per-minute billing gives the same pattern. At an assumed three minutes a call, Dialzara's published tiers ($29 for 60 minutes up to $349 for 1,000, with overage from $0.48 down to $0.35 a minute) come to about $1,181 for all calls, $233 for after hours, $199 for overflow and $376 for both, as of early November 2026.
The all-calls row hides the important number. Of 260 weekly calls, 177 (68%) are ones the office already answers well. In that mode you pay per conversation for them, and they produce no extra jobs, because the person would have taken them anyway. The money in the other rows buys the 83 calls that currently go unanswered.
Put an illustrative break-even beside the costs. Suppose a typical job is worth $300 at a 35% gross margin, so $105 of contribution. Overflow at $135.65 breaks even after about 1.3 recovered jobs a month, after hours at $159.35 after 1.5, both together at $288.91 after 2.8, and all calls at $894.84 only after 8.5. To estimate how many jobs you would really recover, use your log again: ask the AI to count how many missed calls were followed by a call from the same number within an hour. The rest are the callers who did not ring back, and they are the upper limit on jobs recovered. For this firm the sensible answer is after hours plus overflow, at about $289 a month. The tutorial on Jobber's receptionist pricing for a one-van plumber covers the opposite end, where all calls is usually the only option.
Conditional forwarding: the five settings that make overflow work
Overflow runs on conditional call forwarding, a service your carrier or business phone system provides. Unconditional forwarding sends every call elsewhere. The conditional kind sends a call only when a condition is met: the line is busy, nobody answers, or the phone is unreachable. Jobber's help article says most carriers can forward calls after a certain number of rings or outside business hours, and that the steps depend on your provider. Smith.ai's pricing page for its human receptionists adds that some phone systems, such as RingCentral, can be set to forward only during certain hours, which is the same scheduling an after-hours AI mode needs. The ring time before a no-answer forward can often be set in seconds, and on some networks it is capped at 30 seconds.
Write these five settings down before you change anything, and test each one with a spare phone:
| Setting | Choose | Why |
|---|---|---|
| Forward when busy | On, to the AI's number | Catches calls while the office is on another call |
| Forward when unanswered | On, after about 15 to 20 seconds | Long enough for the office to pick up, short enough that the caller has not given up. This is my starting point; adjust it from your log |
| Forward when unreachable | On, if the office line is a mobile | Covers a phone that is off or has no signal |
| Voicemail | Off on the office line, or set to answer after the forwarding delay | Otherwise voicemail answers first and the forward never happens |
| Call waiting | Off on the office line, then test | With call waiting on, a second caller may hear ringing instead of a busy signal, so the busy rule never fires |
The double delay. Jobber's receptionist has an optional answering delay of about two rings, roughly 10 seconds. The help article says that if you use call forwarding, this delay is in addition to whatever your phone provider adds, and recommends turning Jobber's delay off (Google Voice users are the exception; Jobber recommends the delay for them). With 20 seconds at the carrier plus Jobber's 10, a caller listens to 30 seconds of ringing before anyone speaks. Some will hang up and ring the next firm on the list. Remove one of the two delays.
After-hours cover needs a schedule somewhere. Use the scheduling your carrier or phone system offers, so that in-hours calls never reach the AI tool at all. Jobber lets you set separate business-hours and after-hours greetings, but if the receptionist answers every call all day, "after hours" is only a different script and you are in all-calls mode, billed as such. If neither your carrier nor your phone app can schedule forwarding, that is worth knowing before you choose a vendor.
The number you forward to. Jobber needs one of its dedicated numbers to receive forwarded calls, and Goodcall's pricing page says you keep your existing number by forwarding it to the service. Both ask you to leave your published number alone, which is the point: customers keep ringing the number on the van.
Burst-pipe keywords: where the transfer goes in each mode
A keyword rule tells the receptionist to hand the call to a person when the caller uses certain words. Jobber's receptionist page gives "emergency", "no heat", "burst pipe" and a commercial account name as examples. Its help article lists "emergency", "speak to a manager" and "urgent", and offers two ways to hand over: a text to your phone with a snippet of the transcript and a link to return the call, or an immediate transfer. It also sets one rule that catches people out: the escalation contact's phone number must be different from your business number or dedicated number, or the transfer will not work properly.
Write the keyword list from your own calls, not from a template. Ask the AI to read your twenty most urgent calls from last winter, using the notes or transcripts you already have, and list the words callers actually used. Then group them:
TRANSFER NOW (urgent water): burst, flooding, flooded, water coming through the ceiling, water pouring, no water, sewage, overflowing, can't turn it off
SAFETY MESSAGE FIRST, THEN TRANSFER (gas): gas smell, smell gas, gas leak
TRANSFER IN HOURS ONLY: [names of your commercial accounts], speak to a manager, complaint, existing job
TEXT ME, DON'T TRANSFER: no hot water, dripping tap, blocked sink
ADD IF YOU SERVE VULNERABLE CUSTOMERS: elderly, baby, no heating in winterTwo parts of that list need care. For a gas smell, the greeting should deliver a safety message before it does anything else. Your own wording should come from someone qualified, and the usual shape is: leave the building, do not touch switches or flames, and call the gas emergency number from outside. For urgent water, an equally short first instruction ("if you can reach the main stop tap safely, turn it off, and keep away from electrics near the water") is worth scripting, again approved by a qualified plumber. The tutorial on AI receptionists for plumbers: cost, burst-pipe rules and booking limits goes further on what the AI may and may not promise.
Where a transfer goes depends on the mode, and this is the easiest part to get wrong:
| Mode | When | A burst-pipe call goes to | If nobody answers |
|---|---|---|---|
| All calls | In hours | The dispatcher's direct line | The on-call plumber |
| All calls | After hours | The on-call plumber | The owner |
| After hours | Evenings and weekends | The on-call plumber | The owner |
| Overflow | In hours | A second line or the owner's mobile, never the office line that did not answer | The on-call plumber |
In overflow mode the call reached the AI because the office could not take it. Sending an urgent transfer back to the office line is a loop that ends in voicemail. Send it to a number that can pick up when the office cannot. If your tool tries several numbers in order, as Rosie's Growth plan describes with "waterfall transfers" that try multiple numbers until someone answers, put the on-call plumber first, the backup second and the owner third. Whatever the tool, test the whole chain by calling it and saying "burst pipe", then check that a human phone rang.
Where each mode breaks, and how to spot it
Many coverage problems come from the phone settings around the AI rather than from the AI itself. Each of these shows up in a particular way, which is how you find it.
| Failure | How it shows up | Fix |
|---|---|---|
| Forwarding loop | Callers who ask for a person hear ringing, then voicemail; transfers go back to the number they came from | Give the escalation contact a different number from the business line, as Jobber's help article requires |
| Double delay | Callers say it "rang forever"; the log shows the AI answering after about 30 seconds | Set one delay, not two: turn off the receptionist's own answering delay |
| Voicemail answers first | Voicemails arrive for calls that should have forwarded | Switch voicemail off on the office line, or lengthen its ring time beyond the forwarding delay |
| Call waiting hides "busy" | Staff see a second call ringing while the AI never gets it | Switch call waiting off on the office line, then test |
| Spam burns the allowance | The bill climbs; the log shows short calls from the same numbers | Check how your vendor treats spam and what you must do for it to be excluded, such as passing caller ID |
| Schedule gaps | A call on a public holiday, or at 4.45 p.m. on an early Friday, went to an empty office | Put holidays and early finishes into the forwarding schedule, and review it each quarter |
On spam, vendors differ, and the difference affects the bill. Jobber does not count conversations it tags as spam or as having no real interaction. Goodcall's page says spam and wrong numbers do not count towards its unique-customer limit. Smith.ai's AI receptionist page says every answered call counts by default, calls from known spam numbers are filtered out before the AI answers, and you can remove up to 10% of a billing cycle's calls as spam. Ask your vendor in writing what counts, because "answered by the AI" and "billed" are not always the same thing.
A five-call test before you trust a mode
Make five calls from a spare phone, on a weekday and again at a weekend, and write down what happens each time. The longer fifteen-call version is in the tutorial on testing an AI voice agent before it takes real jobs. These five are the ones that test the mode itself.
- The busy test. Hold the office line busy with another phone, then call it. In overflow mode the AI should answer, with the right greeting, within the forwarding delay you set.
- The no-answer test. Let the office phone ring unanswered and time it with a stopwatch. The AI should speak after your chosen total delay, and not after double it.
- The after-hours test. Call at 6 p.m. You should hear the after-hours script, and the booking or message should reach the right inbox.
- The burst-pipe test. Say "burst pipe". The safety message should come first, a human phone should ring within seconds, and that phone should show a number the on-call plumber recognises.
- The regular customer test. Call from a commercial account's number, or say the account name, and then say "speak to a manager". Both should reach the person you named.
For each call, record the time to answer, where the call landed, what the AI said, what your usage page logged, and whether the call counted as a conversation. Ten minutes of this will find most of the failures in the table above before a customer does.
Moving from one mode to another as the firm grows
The right mode this year is not the right mode for ever. Four changes should send you back to the call log:
- The office hires someone. Misses fall, and overflow may no longer pay for itself. After-hours cover usually stays.
- The owner comes off the tools. A firm that began in all-calls mode, because nobody was in, can usually move to after hours once someone answers the phone in the day.
- After-hours volume doubles. One on-call plumber may not be enough, and the transfer chain needs a second route.
- Your billing changes. If a move to a plan with unlimited receptionist use makes the cost the same in every mode, choose on service and customer preference, because some callers still prefer a person.
Weather is the other trigger, and overflow is the dial to turn. On the first hard frost of winter the phones can multiply, so shorten the unanswered delay (from 20 seconds to 10, say) for the first cold week so that the AI picks up sooner, and set it back when the rush ends. A calendar reminder in autumn is enough to remember it.
Whatever you choose, schedule a review every quarter. Re-run the call-log prompt on the most recent two weeks, compare the five numbers with the thresholds above, and check that the forwarding settings still match what you wrote down. A phone provider that changes an account, a new mobile handset or a changed office closing time can quietly undo a setup that worked in March.
Coverage questions plumbing firms ask
Does a call count if the caller hangs up straight away?
It depends on the billing unit. Jobber counts a call as a conversation when the receptionist actively engages, and does not count spam or calls with no real interaction. Other vendors bill per minute, per call or per unique caller. Ask each one what happens to hang-ups and spam before you compare prices.
Can I keep my existing business number?
Usually yes, by forwarding it. Jobber says you keep your number and forward calls from your phone provider, though it needs a dedicated Jobber number to receive them. Goodcall's pricing page says you can keep your existing number by forwarding it. Confirm the forwarding steps with your carrier before you commit.
Do I have to tell callers it is an AI?
Say so in your greeting, for example that you are an automated assistant for the firm. If you have customers in the EU, the AI Act's transparency rule for systems that talk to people has applied since 2 August 2026, so ask your vendor how its default greeting handles it. Do not assume the default wording discloses anything.
What happens when the monthly allowance runs out?
You choose, if the vendor lets you. Jobber offers to continue and pay per extra conversation, or to pause the receptionist, in which case callers can still leave a message but nothing is booked. Pick deliberately before the first busy month, and forward calls elsewhere if you choose to pause.
Further reads
- AI Answering Service for Plumbers: Rosie, Goodcall, Smith.ai or Jobber? — Rosie, Goodcall, Smith.ai and Jobber compared for plumbers.
- Housecall Pro CSR AI vs Jobber's AI Receptionist: Which Suits a Plumber? — Two field-service receptionists side by side for a plumber.
- Can AI Triage Emergency Plumbing Calls Out of Hours? — How AI sorts emergencies from routine calls out of hours.
- Can an AI Dispatcher Replace Your Plumbing Office Dispatcher? — What an AI dispatcher can and cannot take off your office.
- Setting Up an AI Answering Service That Never Misses an Emergency — Setting up an answering service that never misses an emergency.
- AI Answering Service for Contractors: 100 Calls Priced Across Five Vendors — 100 calls priced across five vendors, for contractors.
- AI vs Human Answering Service for HVAC Firms — AI against a human service, written for heating and cooling firms.
- AI Receptionist for a Campground: After-Hours Calls, No Night Warden — Price after-hours phone cover for a campground at $49 to $150 a month and see which calls must still reach a person.
- AI Receptionist for Roofing Companies: Storm-Day Calls and Claim Questions — A storm-week setup for roofers: six call types, an inspection cap, transfer rules, claim wording that stops short of adjusting, and twenty test calls.
- AI Receptionist for Trades: Built Into Your Job Software or Standalone? — Jobber and Housecall Pro receptionists against Smith.ai, Rosie and Goodcall: what each books, transfers and logs, and the maths at three call volumes.
- Best AI for Plumbers: What a Solo, Two-Van and Ten-Van Firm Should Buy — One van, two vans or ten: which AI setup a plumbing firm should buy, what each tier costs a month, and the signs it is time to move up.
- Phone Marketing Software With AI Features: What Trades Should Compare — Missed-call text-back, AI answering, quote follow-up and review requests compared for trades: Jobber, Quo, Podium and others, with a monthly cost sum.
- Water Damage Restoration Leads After a Flood: Answer and Book With AI — A six-question intake script, storm-night priority tiers, overflow answering costs and an insurer-ready photo list for a water damage restoration firm.
- Workiz Genius AI: Which Add-Ons Are Worth It for HVAC or Plumbing — Break-even sums, test calls and rep questions for each Workiz Genius add-on, written for HVAC and plumbing firms deciding what to pay for.
- AI Chatbot for Plumbers: Answer Questions, Collect Photos, Refuse Jobs — Set the scope of a plumber's website chatbot: three lanes, an approved answer sheet, price rules, photo requests, refusals, handover and a 20-message test.
- HVAC Busy Season Checklist: Cope With the Summer AC Surge Using AI — An owner's checklist for the summer AC surge: capacity rules, four triage tiers, overflow answering, text-back, deferred tune-ups and parts prep.
- How to Dispute Google Local Services Leads: A Plumber's AI Evidence Pack — Which Local Services Ads leads Google credits, the proof to keep for each reason, plus an AI call-summary routine and dispute log for a plumbing firm.
- AI Tools and AI Development: The Complete 2026 Guide — the AI hub, including every tutorial in the AI-for-business series.
Sources: Jobber's Receptionist help article and getjobber.com/ai-receptionist; Goodcall, Dialzara and Rosie pricing pages; Smith.ai's receptionist and AI receptionist pricing pages (all checked 1 November 2026); the EU AI Act's application timeline for Article 50 transparency duties.