Cellars, plant rooms, boiler cupboards, tower blocks. The places you actually fill a certificate in are the places with no signal. So certificates work offline end to end: you can start one, fill it in, photograph what you need, get the signatures and sign it off without a single bar.
You can get to it with no signal too. The certificate turns up on the job once you've pressed Arrived, and pressing Arrived works offline — it saves on the phone and sends itself when you're back in range. That used to be the sticking point: no signal meant you couldn't say you'd arrived, so the certificate never appeared to be filled in.
Starting one with no signal
Open the job the same way you always would. If the job's type is set up to produce a certificate, you'll see the usual prompt:
This job needs a CP12 — Start it
Tap Start it and the form opens. The client, property and engineer are filled in from the job, exactly as they would be online.
If you'd already started that certificate earlier, the prompt says "CP12 saved on this phone" with a Carry on button instead. That's deliberate: it stops you accidentally starting a second certificate for the same job.
While you're filling it in
Everything works as normal:
- Photos. Take them as usual. They're held on the phone and uploaded when you're back in signal.
- Signatures. Yours and the customer's, both fine offline. If you've saved your signature before, the one-tap option still works.
- Last year's details. Been to this property before? Mucka still offers to carry over the appliance list, with all the readings blank ready for today's.
Everything you type is saved to the handset as you go, so you don't need to do anything to protect it. There's no "saving" spinner to wait for and nothing to press.
The one time Mucka does say something is if it can't save to the phone either — you'll get "Couldn't save. Check your connection" in red at the bottom of the form. That's rare, and it's worth acting on: come back into signal before you carry on, because that's the only case where what you've typed is genuinely at risk.
The certificate number
A certificate gets its number from the office system, so with no signal there isn't one to give you yet. Rather than showing you a number that isn't real, Mucka says:
CP12 · number on sync
The real number is allocated the moment your phone gets back in signal. Don't read the placeholder out to a customer — there's nothing to read.
There's an upside to this. Because an offline certificate doesn't take a number until it syncs, one you start and then abandon costs you nothing at all.
Signing it off
Tap Approve as usual. Mucka checks the same things it always checks — appliances, signatures, your Gas Safe details — and tells you what's missing if anything is.
Once you approve it, the certificate locks and the label reads:
Issued · syncing
Not "Approved". You've signed it off, and that's real, but it isn't fully issued until the office system has numbered it and produced the PDF. Mucka won't pretend otherwise on a legal document.
Back in signal
You don't have to do anything. The moment your phone reconnects, Mucka uploads everything by itself: the certificate, the photos and the approval. The number appears, the PDF gets produced, and the certificate behaves exactly like any other.
What still needs a connection
- Emailing the certificate to a customer. There's no PDF to attach until it's synced, so Send waits.
- Downloading the PDF. Same reason.
- Reading a certificate you haven't opened on this phone. Mucka can only show you what's on the handset. One that's only ever lived in the office will say "This certificate isn't on this phone" — nothing is lost, it's just not there to read yet.
- The photo scan buttons — a flue gas analyser, or any data plate (appliance, air con unit, burner, cylinder, oil tank). They say Needs signal rather than failing, and typing it in by hand is the fallback.
Common gotchas
- "No room to save more photos on this phone." The handset is running low on space for queued photos. Get back in signal so the ones you've taken can upload, and there'll be room again.
- "This certificate wasn't issued." Rare, but it means the office system refused the approval when your phone synced — usually because something changed at the office end, like a Gas Safe licence expiring. The certificate is editable again and the banner tells you exactly what it needs. Nothing you filled in is lost.
- Nothing saved on the phone at all. If you've never opened Mucka on that handset with signal, there's nothing for it to work from. Open it once with a connection and you're set.
- Don't sign out until it's synced. Work saved on the phone lives on that handset until it reaches Mucka, so signing out throws it away. If you try, Mucka tells you what you're about to lose and gives you the chance to stay signed in — get back in signal, let it send, then sign out. This matters most on a shared van phone, where signing out is also what clears your jobs and customer details off it for the next person.