All posts
Introducing Usage Limits: Automatic Cost Control for Your SIM Fleet
A single misbehaving device (a firmware bug stuck in a retry loop, a sensor pushing raw video instead of a compressed payload) can turn a predictable connectivity bill into an unpleasant surprise. Until now, catching that meant watching usage dashboards and reacting after the damage was done.
Usage Limits, now live in the Simbase dashboard, change that. You can now cap mobile data and SMS usage per SIM directly from the SIM detail page. When a SIM crosses the limit you set, it's automatically disabled and a notification email goes out to your account's technical contact, no manual monitoring required. Pair that with the optional monthly auto-reset, and you've got hands-off cost control running across your entire fleet.
How It Works
Usage Limits are evaluated against the Call Detail Records (CDRs) that Simbase receives from the network. Every time a new CDR comes in, we compare the SIM's cumulative usage for the current calendar month against the cap you've configured. The flow is straightforward:
Usage accumulates as CDRs arrive from the network throughout the month.
The cap is exceeded when a CDR pushes total usage past your configured limit.
The SIM is disabled automatically, and an email notification goes out to the technical contact on your account.
Setting Up a Usage Limit
Getting a limit configured takes about a minute:
Log in at dashboard.simbase.com and open the SIM card you want to configure.
Go to the Usage Limits tab on the SIM detail page.
Set one or both limits:
Data Limit: maximum data usage in GB. The SIM is disabled once usage exceeds this value.
SMS Limit: maximum number of SMS messages. The SIM is disabled once the count exceeds this value.
Optionally, turn on Monthly Auto-Reset to have the SIM automatically re-enabled on the 1st of each month.
The two limits work independently. If you set both a data cap and an SMS cap, the SIM is disabled the moment either one is crossed, whichever happens first.
Need to apply limits across a large fleet rather than one SIM at a time? The dashboard configures limits per SIM, but the Simbase API lets you automate that at scale.
Auto-Reset and What Happens Without It
Enable Monthly Auto-Reset and a SIM that gets disabled by a usage limit is automatically re-enabled on the 1st of the following month, so devices pick back up without anyone touching the dashboard. Leave it off, and the SIM stays disabled until someone re-enables it manually via the dashboard or API.
One thing worth flagging: if you re-enable a SIM mid-month while its usage still exceeds the configured limit, it will simply be disabled again the moment the next CDR arrives. If you want it to stay active, raise the limit before you flip it back on.
An Important Caveat: Data Limits Can Be Exceeded
This is the part worth reading closely before you set a "hard" limit.
Data usage isn't measured continuously in real time; it's measured and enforced based on data sessions, reported via CDRs. That means a SIM can go slightly over its configured limit before Simbase disables it, because the SIM is only disabled once a data session closes and its final usage is reported.
Here's a concrete example:
Data limit: 1 GB (1000 MB)
Current usage: 900 MB (100 MB of headroom left)
The device starts a new session and uses 150 MB
When that session ends and its CDR is processed, the platform sees the limit has been crossed and disables the SIM
Result: the SIM ends up roughly 50 MB over its 1 GB limit
Network operators generate a CDR when a data session closes, when the SIM roams to a different operator, at a fixed interval (commonly every six hours, though this varies by operator), or when an SMS is sent. Simbase evaluates each CDR against your limit rules as it arrives, but there's no guaranteed maximum delay between actual usage and CDR arrival, since that depends on the upstream network operator.
Practical takeaway: if you need a strict hard stop, set your limit slightly below your true maximum to leave room for potential overshoot. How much overshoot to expect depends on the size and frequency of your devices' data sessions.
Usage Limits vs. Auto-Disable
It's easy to conflate this with the existing Auto-Disable function, so here's the distinction: Auto-Disable applies to high-usage (Green profile) SIMs and prevents their data bundle from automatically renewing at the start of a new month. Usage Limits instead monitor actual data and SMS consumption during the month and disable a SIM the moment a threshold is crossed. They're separate features that operate independently, and there's nothing stopping you from using both.
Keep Your Contact Details Current
When a limit is exceeded, the notification email goes to the technical contact on your account, so it's worth a quick check under Settings to make sure that contact information is up to date.
It's also worth being clear-eyed about what this feature is and isn't. Because enforcement depends on CDR delivery from third-party network operators, Simbase can't guarantee a SIM will be disabled at or precisely below your configured limit; Usage Limits are a best-effort safety net, not an absolute hard cap, and you remain responsible for usage incurred before a SIM is disabled.
Try It Now
Usage Limits are live for every SIM in your fleet today.
Head to the Simbase dashboard, open a SIM's detail page, and set your first limit, or read the full documentation for more detail on how CDR timing affects enforcement.
