Scheduled SMS: Send Messages at the Right Local Time
Scheduled SMS lets you queue a campaign for a future date and time so messages leave when recipients are awake and receptive. You still send through your own Android phone and operator plan; the gateway simply holds the queue until the clock says go.
09:00
Asia/DhakaPayday reminders
Queued · 1,240 rows09:15
Device 27OTP SIM reserved
Pinned · no bulk on this path14:00
Asia/JakartaStatement run
Local window · editableTue
RecurringAppointment nudge
Series · cancel any occurrence
Timezones and quiet hours — the part that goes wrong
Clocks look simple until your list spans more than one zone. A schedule that feels polite in your office can ring phones two hours earlier or later for someone else. Quiet-hour expectations and, in some markets, regulator-imposed sending windows make that mistake expensive as well as rude.
For transactional traffic such as OTPs and shipping updates, timing is usually "as soon as the event happens." For reminders and marketing, prefer the patterns in transactional SMS only when the content is truly transactional; promotional campaigns belong in permitted daytime windows.
What you can and cannot schedule
These are the practical limits teams ask about before they trust an unattended queue.
| Detail | What to expect |
|---|---|
| Earliest scheduling | Any future moment after the queue is confirmedThere is no artificial "minimum lead time" beyond practical clock skew of a few seconds. |
| Latest scheduling | Days or weeks ahead for campaign planningLong-horizon schedules still depend on the same device remaining online and funded when the moment arrives. |
| Edit or cancel a queued campaign | Allowed until the scheduled window opensAfter sending starts, stop further work from the queue; messages already handed to the handset follow normal delivery behaviour. |
| Device offline at the scheduled moment | The queue waits and resumes when the device reports backMessages are not silently dropped. You still want last-seen alerts so a dead phone is noticed quickly. |
| Recurring sends | Supported for repeating reminders on a fixed cadenceEach occurrence is its own queued run. Cancel the series if the reminder should stop. |
| Per-recipient send windows | Optional when you store each recipient's local timezoneUseful for international lists where one wall-clock time would wake some people and miss others. |
| Interaction with device throughput | The schedule starts the queue; pacing still follows device rateA large list that fires at 09:00 still takes as long as the connected SIMs can send — scheduling does not compress the send window. |
Throughput still depends on how many phones and SIMs you connect. Scheduling does not create a faster path through the carrier. If a morning campaign must finish before noon, size the fleet the same way you would for an immediate send — see multi-device and dual SIM routing. Delivery outcomes remain visible through delivery reports once each message leaves the handset.
What scheduled SMS means
Scheduled SMS is a send you prepare now and fire later. You build the audience, write the message, pick a future date and time, and the gateway holds that work in a queue. When the moment arrives, the connected Android device starts delivering — the same way it would for an immediate campaign, only delayed until the clock says the window is open.
That is different from rate-limited pacing on an immediate send. Pacing spreads a list that has already started so the handset and carrier are not flooded. Scheduling decides when the list begins. Teams use SMS campaign scheduling for payday reminders, appointment nudges, statement runs, and any promotional traffic that should land during local business hours rather than whenever someone pressed send. The messages still leave from your own SIM using your operator credit; see pricing for how device count and send volume map to plans.
- 01
Scheduled SMS queues a send for a future date and time; the connected Android device works the queue when that moment arrives.
- 02
Timezone choice decides whether the campaign lands during business hours or at 3am for someone two zones away.
- 03
If the device is offline at the scheduled moment, the queue waits and resumes rather than silently dropping messages.
- 04
You can cancel or edit a queued campaign until the send window opens; recurring reminders are supported as separate queued runs.
- 05
Service pricing follows device count and total SMS sent; you supply the phone, SIM, and operator SMS credit.
Scheduling a campaign step by step
The flow mirrors an immediate campaign with two extra decisions: when to start, and which clock to trust. Audience work usually starts from contacts and lists or a spreadsheet import via bulk SMS from Excel or CSV.
- 01
Pick the audience
Choose a saved contact list, upload a fresh segment, or pass recipients from your own system. Filter for consent and opt-outs before the campaign enters the queue — a schedule does not fix a bad list. - 02
Write the template
Compose the message once. If you use merge fields, preview a few rows so variable lengths do not push part of the list into an unexpected second segment. - 03
Choose the date and time
Set the future moment when sending should begin. This is the wall-clock trigger for the queue, not a soft suggestion — the device starts working the list when that moment arrives. - 04
Choose the timezone basis
Decide whether the clock is yours, a fixed campaign zone, or each recipient's local time where you have that data. Getting this wrong is the most common reason a scheduled SMS lands at an awkward hour. - 05
Confirm the device that will carry it
Pin the campaign to a specific phone and SIM, or to a routing group. Check that the handset is online, charged, and holding operator credit before you leave the queue to fire unattended. - 06
Review the queue before it fires
Read the recipient count, the rendered preview, the scheduled instant, and the chosen device. Cancel or edit here if anything looks off — once the window opens, the campaign behaves like an immediate send.
Scheduling from the panel versus an immediate API send
Prefer the web app schedule UI for queued campaigns you need to see, cancel, or edit. Immediate API sends use POST /messages with scheduleAt (ISO-8601 UTC). Confirm fields in the API reference before scripting them.
curl -X POST "https://app.sms-gateway.app/api/v1/messages" \
-H "Authorization: Bearer $SMS_GATEWAY_API_KEY" \
-H "Content-Type: application/json" \
-d '{"to":["+14155552671"],"text":"Reminder: your invoice is due tomorrow.","type":"sms","scheduleAt":"2026-09-01T09:00:00Z"}'
# Times are ISO-8601 UTC unless the string carries an offset.
# scheduleAt is refused beyond 38 days. PATCH /campaigns/{id} can re-time a campaign.Your own cron or job scheduler is an equally valid pattern. Use the gateway queue when the schedule should survive an app restart and stay visible in the panel. Use your own scheduler when the trigger is already part of a larger workflow — for example an invoice job that only knows the send time after a billing run finishes — and post an immediate send at that moment instead. Either way, you still bring the Android phone, the SIM, and the operator SMS credit; the service fee follows device count and the messages actually sent.
Practical answers about schedule SMS messages
Short replies to the questions that come up after the first scheduled campaign is live.
Can I cancel a scheduled campaign after I save it?
Yes, as long as the scheduled window has not opened. Open the queue, cancel the campaign, and nothing leaves the device. Once sending has started, you can stop remaining work, but messages already given to the handset continue through normal carrier delivery.
What if the campaign misses its window because the phone was offline?
The queue holds and resumes when the device comes back online rather than discarding the list. Check last-seen and battery alerts if a morning schedule regularly slips into the afternoon.
How do daylight-saving changes affect a schedule?
Schedules stored with an explicit offset or a named zone follow that zone's rules. Prefer IANA zone names over a bare local clock if your market observes daylight saving, so a spring-forward or fall-back does not silently shift the send by an hour.
Are recurring reminders supported?
Yes. You can set a repeating cadence for reminders such as billing notices or appointment nudges. Each occurrence is queued separately, and you can cancel the series when the reminder should stop.
If something looks wrong in production and you need a human review, support typically responds within 24-48 hours. Include the campaign id, the scheduled timestamp with timezone, and the device id so the queue state can be checked without a long back-and-forth.
Regional notes for SMS campaign scheduling
Quiet hours, promotional windows, and local business norms change what a “good” schedule looks like.
India
Promotional traffic sits inside restricted sending windows and DND rules. Schedule SMS campaign traffic for permitted hours and keep transactional wording separate from marketing blasts.
USA
State-level quiet-hour expectations matter even when your own clock looks fine. Prefer local business hours for promotional SMS, and treat early-morning or late-evening schedules as a compliance risk.
Bangladesh
Local business-hours norms and payday cycles drive reply rates. Schedule statement and collection reminders for mid-morning on working days rather than Friday evenings.
Indonesia
The country spans multiple timezones. A single Jakarta clock for a national list can land mid-morning in one province and far too early in another — use per-recipient timing when the list is truly national.
More markets and timing context live on the SMS gateway by region hub. Match the schedule to the market, then match the fleet to the deadline.
Related features on the same fleet
These run on the same phones, the same account, and the same REST SMS API— no extra product silos.
SMS Auto-Reply & STOP Keywords
Answer common keywords automatically and record opt-outs the moment they land.View feature →USSD Gateway: Run USSD from an API
Trigger USSD codes such as balance checks and read the operator response back through the API.View feature →Two-Way SMS: Replies on Your Own Number
Keep the conversation on the number you sent from and route replies into your systems.View feature →Common questions about Scheduled SMS
Straight answers for teams evaluating this feature for production OTP, bulk, or two-way traffic.
Run scheduled sms on your own SIM
Install the Android app, pair a device with operator SMS credit, and test this feature in the panel or over the API. Paid plans are metered by devices and SMS send volume.