Android SMS sending limits and how to work within them
Three layers limit how fast an Android gateway can send: the operating system, the carrier and the physics of one radio per SIM. This page states what is documented, dates it, and says plainly what nobody publishes.
The three layers of limits
| Layer | What it does | What is documented |
|---|---|---|
| Android OS | Rate-limits SMS per app; over the limit the system asks the user to confirm each batch | AOSP's default policy: 30 messages per app per 30-minute window (see below) |
| Carrier | Throttles or blocks SIMs that send like a machine; patterns differ per plan | Almost nothing public — treated as unknown below |
| Physics | One SIM is one radio: sending is serial, and long messages are billed per part | 153 GSM-7 / 67 UCS-2 characters per part, from 3GPP TS 23.040/23.038 |
The Android limit, with its source
Android's default policy, defined in the AOSP class SmsUsageMonitor, lets an app send
30 SMS per 30-minute window; past that, the system shows the user a dialog
(“…is sending a large number of SMS messages”) and each further batch needs a tap.
Device makers and carriers can change the constants, so your phone may allow more or less. Source:
AOSP SmsUsageMonitor (default check period 1,800,000 ms, default maximum 30),
consistent with long-standing secondary documentation; observed 2026-11. We could not re-confirm the
current constants from the live AOSP page this month, so treat 30/30 min as the documented default,
not a guarantee for your device.
What this means in practice: an unattended bulk campaign must not rely on a human tapping that dialog. Pace the queue below the limit instead of racing into it.
Carrier throttling: the honest unknown
Carriers watch for machine-like sending: constant inter-message gaps, identical text, round-the-clock volume. The consequence is throttling, silent drops or a blocked SIM, and the thresholds are not published. Any page that quotes you a universal “messages per day per SIM” figure is guessing. The working method is empirical: send a small batch, watch the delivery reports, raise the daily quota per SIM only while reports stay clean, and keep bursts short and human-shaped.
Working within all three layers
- Pace, don't burst. Keep the send rate under the Android window; slow beats stopped.
- Quota per SIM. Set a daily quota below your observed safe level so the queue slows before the carrier acts.
- Spread across SIMs. Five SIMs at a gentle pace beat one SIM at five times the pace; see the multi-SIM guide.
- Count parts, not messages. A 200-character GSM-7 text is two billed parts; the arithmetic is on the segmentation table.
- Schedule into waking hours. Quiet-hours scheduling is both a compliance feature and a throttle-friendly one.
- Read the reports daily. A rising failure rate is the earliest sign of carrier throttling.
This guide is part of the Android gateway cluster: overview, multi-SIM, rate limits, troubleshooting.
Questions about sending limits
What is Android's SMS sending limit?
The documented AOSP default is 30 messages per app per 30-minute window, after which Android asks the user to approve each further batch. Device makers and carriers can change the constants, so test on your own hardware.
Can the Android limit be raised or removed?
Not from inside an ordinary app. Root-level tweaks exist but are outside what we support; the reliable approach is pacing the queue below the limit and spreading volume across SIMs.
How many SMS per day can one SIM handle?
There is no honest universal figure: carriers do not publish their thresholds, and they differ per plan. Establish your own ceiling with a small test campaign and clean delivery reports before raising the quota.
Does MMS count against the same limits?
MMS travels a different carrier path and has its own constraints (size, APN, carrier policy). Treat the Android SMS window as SMS-specific and test MMS volume separately.
Will slowing down hurt throughput badly?
It caps throughput per SIM, yes. That is why volume senders scale by adding SIMs and phones, not by racing a single one: the multi-SIM guide shows the layout.