What actually arrives after hours
Most of it is routine and answerable from information you already hold: which day recycling goes out, the buzzer code, whether the parking spot is assigned, when the exterminator is coming back, whether a package was left with the super.
A smaller share is a real repair that can wait until morning, and needs an acknowledgement and a date rather than a truck.
A small number cannot wait: gas, fire, flooding, no heat in winter, an electrical hazard, a lockout at night. These are the ones the whole system exists for.
The cost of the routine share is not the work; it is that it makes you stop reading. Once a phone stops being answered, the emergency arrives in the same silence as everything else.
Why voicemail is the expensive option
A voicemail checked at 8 a.m. treats a burst pipe reported at 11 p.m. as a nine-hour problem. Remediation cost scales with time far more sharply than plumbing cost does.
It also produces no record. Section 20 obligations are judged on when you knew, and "the message was in the box overnight" establishes that you were told and did nothing for nine hours.
What the options cost
A live answering service charges per minute or per call and reads from a script. It captures the message reliably, but it does not know which unit the caller lives in, cannot answer the routine questions, and will pass most of them to you anyway.
An on-call rotation only exists if you have staff, and it needs a written escalation rule or the rota just moves the anxiety around.
An assistant that answers on the channels people already use — text, phone, web — can answer the routine share from your own property notes, collect what a trade would need on the rest, and page a human only when the report meets an emergency definition you set in advance.
The rules that make any of these work
Write the emergency definition down before you need it, and make it the same definition at 2 a.m. as at 2 p.m. Gas, fire, flood, no heat in winter, electrical hazard, night lockout.
Acknowledge everything immediately, even when the answer is that it waits until morning. Silence is what escalates.
Never let an after-hours answer promise a time nobody can keep. A booked window that is missed does more damage than an honest "a trade will call you before noon".
Route anything legal — rent, notices, deposits, eviction, disputes — to the Landlord and Tenant Board or a lawyer rather than answering it at midnight.