This article explains where the numbers in your dashboard come from, why they sometimes lag behind what a device is doing right now, what actually counts as billable data, and what "overage" means when your account is prepaid rather than billed monthly.
How usage is measured
Simbase doesn't monitor traffic continuously. Instead, the network operator sends a Call Detail Record (CDR) to Simbase whenever:
A data session closes, because the device disconnected, the session timed out, or the device moved to a different operator
An SMS is sent or received
Each CDR records how much data, or how many messages, that session used. Simbase adds it to your running usage total and deducts the corresponding cost from your balance.
There's no live meter. The dashboard shows usage as of the last CDR Simbase has received, which is usually close to real time but can lag, especially for long-running sessions or operators that batch their CDRs.
Multi-day sessions are dated to when the session started
A session doesn't generate a CDR until it closes, however long it runs. If a session stays open for several days, all of its usage is reported against the day it started, not the day it ended. A session opening on the 28th and closing on the 31st shows its entire total against the 28th. If you reconcile daily reports, or totals near a month boundary, a long session can make an earlier day look busier than it did at the time.
Measuring units
Dashboard and billing figures use decimal units: 1 gigabyte = 1,000 megabytes = 1,000,000 kilobytes = 1,000,000,000 bytes. The Simbase API reports usage in binary gigabytes instead, so convert before comparing the two. See Usage Guard Toolkit.
What counts as billable data
A few rules explain most of the gap between what a device thinks it sent and what Simbase bills:
Sessions are rounded up to 1 kB. A session that moves 234 bytes is billed as 1 kB.
Costs are calculated to four decimal places. Anything smaller than 0.0001 is rounded up to 0.0001.
Protocol overhead is billed. Signalling traffic isn't, but the handshakes, keep-alives, pings, and encryption a device generates around your actual payload are.
Traffic is billed in both directions. Inbound and outbound both count.
On a SIM with a public IP and an open firewall, inbound traffic is billed even when you didn't ask for it. Anything that reaches the device from the internet counts, including unsolicited scanning. See Public IPs.
A device that opens many short sessions will therefore bill higher than its own byte counter suggests, because each session is rounded up independently.
Why this matters for your balance
Because deductions happen when CDRs arrive rather than the instant data is used:
Your displayed balance can be briefly ahead of what's actually been used, because a long session hasn't been billed yet
A burst of CDRs arriving together can drop the balance sharply, even though the usage was spread over hours
If your balance is very low, a delayed CDR can push it to zero after the usage already happened. See Set up billing for what happens at zero balance
None of this changes the total you're charged, only when the deduction appears.
What "overage" means on a Simbase account
On a postpaid plan, "overage" usually means an extra fee for exceeding an included allowance. Simbase doesn't work that way:
There's no included allowance to exceed. Every MB and every SMS is charged from your balance at your plan's rate, from the first one
There's no overage fee. Going over a cap you set yourself doesn't cost extra per MB. Your balance simply depletes, and once it reaches zero your SIMs are disabled until you top up
So on most profiles, "overage" really means a SIM using more than you expected. It shows up as your balance dropping faster than planned, not as a surprise line on an invoice.
Green profile: a real allowance and a real overage charge
Green profile SIMs, commonly known as High Data SIMs, are prepaid on a monthly data allowance rather than pure pay-as-you-go:
Each Green SIM includes 10 GB of data per month, prorated for partial months. A SIM activated mid-month gets a proportional share of that month's allowance
Data used beyond the allowance is billed as overage, at a flat rate per additional GB
The overage rate depends on your Green plan and billing currency. Check the plan details on the SIM for the rate that applies to your account
On a Green SIM, "overage" means what it does on a postpaid plan: a real included allowance, and a real per-GB charge once you pass it. See SIM profiles for how Green compares to the rest.
Download a usage report
Sign in to dashboard.simbase.com.
Open SIM cards and go to the Usage tab.
Click Export.
An Excel or CSV file is generated containing each SIM's activity and data consumption.
Set your own cap with Usage Limits
To stop a SIM automatically once it passes a set amount of data or SMS in a month, use Usage Limits. It runs on the same CDR mechanism described above: Simbase disables the SIM once a CDR shows the cap has been passed, which means a SIM can finish slightly over its cap before it's disabled. That overshoot is explained in full in that article.
If you need cost protection rather than a usage cap, auto-recharge and the low-balance alert are the more direct tools.
Common questions
The CDR arrived late. Operators batch usage records rather than streaming them, so there's a normal delay between a session ending and it appearing in your total.
Three reasons, usually in combination. Each session is rounded up to 1 kB, so a device opening many small sessions bills more than its own byte count. Protocol overhead such as handshakes and keep-alives is billed. And traffic is counted in both directions, including anything arriving unsolicited if the SIM has a public IP with an open firewall.
On pay-as-you-go profiles, no. Every MB is charged at the same rate regardless of how much you've used that month. Green is the exception: once you pass the monthly allowance, additional data is billed at a flat per-GB overage rate.
No. You're charged for the data you actually used, at the normal rate, with nothing extra. The overshoot is just usage that happened before the disable took effect. See Usage Limits.
Related
Billable items, everything that draws down your balance
SIM profiles, how Green compares to the other profiles
Usage limits, set a per-SIM monthly cap
Set up billing and add balance, low-balance and empty-balance alerts
Set up auto-recharge, avoid running out of balance altogether
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