Usage Limits are caps you set on data and SMS usage per SIM per calendar month. When a SIM hits the cap, Simbase automatically disables it and notifies you. Combined with the optional monthly auto-reset, this gives you hands-off cost control for a fleet, with one important caveat: caps are checked when usage records arrive from the network, not in real time, so SIMs can overshoot the limit before being disabled.

This article covers how the limits work, how to set them, and what overshoot to expect.

How it works

Usage Limits are checked against Call Detail Records (CDRs), the usage records an operator sends to Simbase. A CDR arrives when:

• A data session closes

• The SIM roams to a different operator

• A fixed interval elapses (typically every 6 hours, varies by operator)

• An SMS is sent

When Simbase receives a CDR, it adds the usage to the SIM's running calendar-month total and checks against the configured cap. If the new total exceeds the cap, the SIM is disabled and an email is sent to the technical contact on the account.

CDR arrives → usage total updated → compared to cap → SIM disabled if exceeded

There's no continuous, real-time monitoring. The system only knows about usage that's already been reported by the network.

Overshoot

Example

• Data limit: 1 GB (1000 MB)

• Current usage: 900 MB (100 MB remaining)

• The device starts a new data session and uses 150 MB

• The session ends; the CDR arrives; total usage is now 1050 MB

• Simbase sees the cap is exceeded → disables the SIM

Result: the SIM ended up ~50 MB over the configured 1 GB limit.

The amount of overshoot depends on:

• Session size. Longer sessions mean more potential overshoot.

• Session frequency. Frequent short sessions mean closer to real-time enforcement.

• Operator CDR delivery cadence. Some operators batch every 6 hours, others longer.

Best practice for a strict ceiling: set the limit slightly below your absolute maximum. If you can't afford to go over 1 GB, set the cap at 950 MB or 900 MB and treat the headroom as overshoot buffer.

Set Usage Limits on a SIM

1. Sign in to dashboard.simbase.com.

2. Open the SIM you want to configure.

3. Click the Usage Limits tab.

4. Configure one or both:

   • Data limit. Set the value in MB or GB, whichever you prefer (1 GB = 1000 MB). The SIM is disabled when usage exceeds it.

   • SMS limit. A count of messages. The SIM is disabled when the count is exceeded.

   • Optionally enable Monthly Auto-Reset.

5. Save.

Both limits are independent. If you set both, the SIM is disabled as soon as either is exceeded.

Monthly Auto-Reset

When auto-reset is on:

• A SIM disabled by Usage Limits is automatically re-enabled at 00:00 UTC on the 1st of the next calendar month.

• Usage counters reset to zero on the same schedule.

• No manual intervention needed.

When auto-reset is off:

• The SIM stays disabled until you manually re-enable it.

• Usage counters still reset on the 1st of the month, but the SIM stays off until you act.

Choose auto-reset when:

• You want predictable monthly recurring usage with hard caps but automatic resume.

• You don't want overnight on-call for low-balance / over-cap events.

Choose manual re-enable when:

• A SIM going over its cap is a real signal something is wrong (firmware bug, compromised device, unexpected behaviour) and you want to investigate before letting it run again.

Re-enable a SIM mid-month

You can re-enable a disabled SIM at any time, from the dashboard or API. But:

If the SIM's usage already exceeds the limit, it will be disabled again as soon as the next CDR arrives, typically within hours.

To keep it active for the rest of the month, raise the limit before re-enabling.

Usage Limits vs other "stop the SIM" features

See Auto-Disable function, SIM state, and Usage Guard Toolkit (DIY) for the others.

Common questions

Related

• Usage Guard Toolkit (DIY), higher-frequency external check

• Auto-Disable function, calendar-based disable

• SIM state, manual enable/disable

• Billable items, what counts toward your usage