Offline field-service evidence: from the phone to accepted work
The photo is on the technician’s phone, but the office has not received it. What a service app should show when internet drops, an upload repeats or the evidence is not enough to close the job.
Do saved, received and accepted mean the same thing?
Your technician finishes a visit in a warehouse without coverage. They take photos, complete a checklist and request an acknowledgement. Their screen says saved, but the office does not have those files. If both assume the job is closed, the pending work has no owner. Define these states before asking for a finish button:
| State | What it establishes | What remains |
|---|---|---|
| Saved on this phone | The app verified that it retains the capture and its files on the device | Receive and verify them in the office system |
| Upload pending or outcome to verify | An attempt does not yet have confirmed receipt | Check whether it arrived before creating another record |
| Received by the office | The central system identifies the capture and has its required files available | Review the work and the quality of the evidence |
| Correction requested | The reviewer recorded what is missing or why it is not accepted | A new version linked to the previous record |
| Accepted for closure | An authorized person reviewed the version against the agreed requirements | Collection or invoicing, where applicable, follows its own rule |
Sending the form also does not establish that all its photos arrived. Ask for a visible list of pending and received files, and a rule that prevents the package from appearing complete while one is missing. Until the office receives a change, it should show the latest information available and when it was updated.
A connection indicator does not establish receipt. MDN explains that a browser can report an available network without internet access. Confirmation should come from the received record rather than the Wi-Fi icon.
What does the customer acknowledge when signing?
Choose the meaning and display the wording before acknowledgement. “I received the visit and this report” can leave technical review pending. “I accept the work described in this version” expresses a different decision. A technician must be able to record that the person is unavailable or does not accept, without inventing a signature to close the job.
Link the acknowledgement to the order, report version, person giving it and what they recognize. If the described work or a material condition changes later, retain the earlier acknowledgement and request the agreed review. This organizes an operational decision; it does not determine a signature’s legal validity.
Worked example: one visit, two technicians and a lost response
Before departure, both phones downloaded ST-104 and its requirements. Lucía’s capture is EV-104-A, version 1. It remains the same record during retries; a later correction becomes version 2 and retains the link to the first.
| Step | What happens | Required outcome |
|---|---|---|
| 09:10 · Offline capture | Lucía records a reading, photo and acknowledgement in EV-104-A v1 | Show saved on her phone and awaiting receipt; zero accepted closures |
| 10:00 · Response lost | The office saves the package, but coverage drops before the phone receives confirmation | On the phone: outcome to verify. At the office: one received capture, still not accepted |
| 10:05 · Repeated upload | Lucía sends EV-104-A v1 again without changing its files | Recover receipt of the same record; create neither a second capture nor a second closure |
| 10:08 · Technicians disagree | Marco uploads an observation that the fault remains; Lucía had marked the work finished | Retain both observations and leave the difference for review; do not overwrite one with whichever arrives last |
| 10:12 · Evidence rejected | Elena cannot read the measurement in the photo and requests correction | Record the reason, responsible reviewer and rejected version; the order stays open |
| 10:45 · Inspection completed | The technicians check the equipment again and Lucía adds a readable reading and photo in v2 | Retain v1 and its rejection; receive v2. A new photo does not automatically resolve the disagreement |
| 10:55 · Closure reviewed | Elena verifies v2, the explanation of the fault, Marco’s observation and the acknowledgement’s scope | Accept that version only if requirements are met; record who decided and when |
At 10:00 the phone’s outcome is unknown, even though the exercise states that the office saved the package. Your test must inspect both screens. Do not read “no response received” as “it did not arrive” or “the work is accepted.”
Repeating an upload and correcting a report are different actions. The first recovers receipt; the second adds a version with a reason and author. Also agree what happens when the same reference arrives with different files: stop for review rather than silently replacing received evidence.
Commercial products also need rules for concurrent changes. Microsoft documents conflicts between technicians and dispatchers, with resolution options depending on configuration. This test proposes retaining and reviewing the disagreement; establish whether the chosen configuration can do that before buying.
Which dates, devices and permissions need review?
- Three separate moments: when the phone says capture occurred, when the office received it and when the reviewer accepted it. Retain the time zone and test a slow device clock; do not order decisions solely by that time.
- The order available before departure: which visits, forms and data each person can access offline, and when they downloaded them. A later reassignment may not yet be on that phone.
- The actual device: model, operating system, app or browser version, available space and camera permission. Test closing and reopening the app, restarting the device and sending your team’s usual photo sizes.
- Actions by responsibility: technicians record their work; customers give the defined acknowledgement; reviewers accept or request correction. Decide who may reassign, correct or access files from other visits.
- Revoked access: when reconnecting, check that the person is still authorized before admitting changes or displaying new files. Assign responsibility for recovering pending work from a disabled account; do not assume revocation immediately erases a disconnected phone.
OWASP recommends checking permissions on every request. Ask for a test where a technician tries to open a photo from another person’s order or approve their own closure without permission. Access must be rejected even with a saved link.
Browser storage is not a backup. MDN describes space limits, data removal and different conditions in private browsing. For a web app, agree how it detects a failed save and protects pending records; verify that behavior on each device. Do not clear data or reinstall to fix a pending upload before agreeing how to recover it.
What should you ask a supplier before choosing an app?
An ST-104 demonstration with interrupted coverage is more useful than a feature list. Ask to see which tasks work offline, which need preparation and which need internet again. Microsoft Field Service requires prior configuration and data download, and documents network-dependent features. Do not infer that every feature or device behaves the same way.
| Bring to the demonstration | Verify | Stop acceptance if |
|---|---|---|
| An order and its requirements | It opens and accepts captures without coverage after preparing the device | Only the form that was already open works |
| A missing, blurred or wrong-order photo | It stays pending or is rejected with a visible reason | A success screen allows closure without review |
| A lost response and repeated upload | The office retains one receipt for the same capture | Each retry creates another report or closure notification |
| Two people and a revoked account | Disagreements and permissions follow the written rule | The last upload deletes earlier work or grants access to someone else’s data |
| A restart and little free space | Pending records return or a failed save is explicit | The app claims to save something it cannot recover |
First evaluate whether an existing app represents your visits and passes these tests. An adaptation may be enough; custom work is justified when a necessary rule, offline task or viable connection to your operation is missing. The process-documentation guide helps agree responsibilities and exceptions before turning them into screens.
If closure must reach your ERP, continue with connecting a system without replacing it: receiving evidence and recording an ERP operation also need separate confirmations. For control of accounts and devices, review digital keys.
For a freight delivery, also distinguish the recipient’s acknowledgement, received files and review by the person closing the trip. Replace ST-104 requirements with your delivery order and proof; an equipment inspection does not describe that whole process. See our approach to freight-transport software.
Bring a representative visit using fictional data, the form, acknowledgement wording and the phones your team will use. Use the scope worksheet to specify who reviews and which tests they accept. See our approach to app development and software for service businesses.
Primary sources reviewed October 7, 2026. The states and ST-104 propose an operational test; they do not describe an installed app, guarantee file retention or establish a verified Nightly implementation.
Frequently asked questions
Not by itself. First verify that the file remains on the phone, then that the office received the complete package, and finally that an authorized person accepted the work against agreed requirements. The state must show which step remains.
Keep the capture reference and check its receipt. In ST-104, the office saved EV-104-A v1 even though the phone lost the response. Resending the same capture should recover that record rather than create another visit or closure.
Define and display what the acknowledgement recognizes. Receipt of a visit or report can leave technical review pending. Retain the accepted version and separate the acknowledgement from permission to close and from any collection of payment.
Agree how the system retains observations and who decides when they disagree. Test that the second upload does not silently erase the first. A new photo also does not automatically resolve a disagreement about the work performed.
Check the specific tasks and devices. Orders and forms may need to be downloaded first; maps, new assignments and remote lookups may need connectivity. Test capture, restart, low storage and later upload with your configuration before operational use.
Sources
- Configure offline data synchronization — Field Service mobileMicrosoft
- Navigator: onLine propertyMDN Web Docs
- Storage quotas and eviction criteriaMDN Web Docs
- Authorization Cheat SheetOWASP
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