Why Is My Soracom Air for Cellular Data Usage or Bill Higher Than Expected?

If Soracom Air's data traffic volume is higher than expected, the main cause is often communication that was not taken into account, such as DNS queries, HTTP Keep-Alive, or packet overhead. If your bill is higher than expected, charges other than data usage, such as daily basic fees or plan fees, may also contribute.

Common Causes for High Data Usage

From previous cases, here are various examples of communication that can cause extra traffic:

• Name resolution: DNS queries occur when accessing servers by hostname.
• Keep-alive: TCP, HTTP, or MQTT communication often uses keep-alive packets to maintain connections.
• Time Synchronization: Protocols such as NTP.
• Packet Overhead: When communicating via Soracom, each packet uses Ethernet, IP, UDP, and GTP headers as it travels through a cellular network. This creates a total header size of 50 to 54 bytes. These additional bytes are included in a SIM's data usage. For more details, please review the Data Usage Calculation documentation.

Analyzing Traffic

Packets can be captured and analyzed using Soracom Peek. Peek will allow you to analyze the packets to determine the total size that is being sent and identify unexpected traffic sources.

Monitoring and Checking Data Usage

If you need to check the specific usage of a SIM card (e.g., why a specific SIM ID has high usage), you can monitor this via the User Console or API.

User Console

1. Log in to the User Console.
2. Select the SIM you wish to investigate and click Details.
3. Click the Historical charts tab.
4. Monthly cumulative total: Shows the cumulative total by day for the current month.
5. Data usage: Shows historical data usage by month, day, or hour.

You can also view data usage from the Usage statistics screen in the ☰ Menu, which lets you search for SIMs by SIM ID, Name, or Group name.

For more information, refer to the Checking Data Usage documentation.

Downloading Data Usage History

To compare usage across all SIMs in your account, open the Service usage history screen from the ☰ Menu, select a time frame, and click Download. Two CSV reports are available:

• Last 6 months (monthly) - Total monthly data usage of each SIM.
• Last 90 days (daily) - Total daily data usage of each SIM.

Each row includes the SIM's IMSI, SIM ID, name, tags, group, the date (UTC), and the connection type in COUNTRY-PLAN format, along with uploadByteSizeTotal, uploadPacketCountTotal, downloadByteSizeTotal, and downloadPacketCountTotal. Data amounts are reported in bytes (1,024 bytes = 1 kB, 1,024 kB = 1 MB). For details, refer to the Data Usage documentation.

Programmatic Usage

You can use the Soracom API to get the data usage of a particular SIM programmatically. Use the getAirStatsOfSim API (GET /stats/air/sims/{sim_id}) to retrieve data usage details. You can set the period parameter to month, day, or minutes. When specifying minutes, the minimum interval is approximately 5 minutes, and history is available for the past 32 days. Monthly and daily history is available for the past 18 months.

To export a usage report CSV for all IoT SIMs in your account, including terminated IoT SIMs, use the exportAirStats API (POST /stats/air/operators/{operator_id}/export).

Identifying Which Traffic Contributes to Data Usage

Soracom's data usage records report the total uploaded and downloaded bytes and packets for each SIM, aggregated by month, day, or minute, and categorized by country and plan. To narrow down what is consuming data:

• Find when usage occurs: Use the hourly charts in the User Console, or the minutes period in the getAirStatsOfSim API, to identify specific time windows with high usage.
• Compare upload and download: Check whether usage is mostly uplink (data sent from the device) or downlink (data received by the device).
• Review sessions: Each time a data session is created, a session log is recorded in the SIM's Session details. Frequent sessions may indicate that the device is repeatedly disconnecting and reconnecting.
• Inspect the traffic itself: Use Soracom Peek to capture packets as they pass through Soracom, so you can see what destinations your device communicates with and which traffic accounts for the most data.

Controlling and Restricting Data Usage

To prevent unexpected overages, you can use the Soracom Event Handler to set up notifications or bandwidth control. For example, Event Handler rules can run when a SIM's daily or monthly data traffic, or its monthly uplink or downlink traffic, exceeds a limit you specify. Actions include deactivating the SIM, reactivating it the following month, sending an email notification, or calling a webhook.

For an example implementation, see our Disable SIMs That Use More Than 25MB in a Month configuration.

Troubleshooting Network vs. Usage Issues

If you are investigating why a SIM is consuming data or why it is offline, consider the following scenarios described in the Diagnostics and Basic Connectivity documentation:

• No Data Usage Recorded: If Soracom has not recorded any data usage, there may be an issue with the local network operator, such as a poor signal or temporary local outage. This prevents IP packets from reaching Soracom.
• Data Usage Recorded but No Connectivity: If usage is recorded but data does not arrive at your server, there may be an issue with your server's firewall or network routing. You can use Soracom Peek to capture traffic as it passes through Soracom to check for blocked traffic.
• Intermittent Connection: A device may successfully create a data session but suffer from poor signal, causing frequent disconnects and reconnects.

Understanding Data Charges

If you notice unexpected costs (e.g., a specific charge amount like €3.70), remember that Soracom calculates data charges based on:

1. Billable Data Usage: Including the packet overhead mentioned above.
2. The SIM Plan: Whether it is Pay-As-You-Go or a bundled plan.
3. Location: The country where the data was used.

Overage prices for bundled plans and per-country rates for Pay-As-You-Go plans can be found in the Pricing and Fee Schedule.

Charges Other Than Data Usage

If your bill is high even though you only sent a small amount of test data, the difference is likely due to non-data charges. Soracom services are postpaid, and all charges within a month are aggregated at the end of the month. Depending on your SIM and plan, your bill may include:

• Daily basic fees: A basic fee is charged for each day based on the SIM's subscriber status (Ready, Active, Inactive, or Suspended/Standby). When a SIM in Ready or Standby status registers to a network, Soracom automatically changes it to Active.
• Monthly plan or bundle fees: SIMs with monthly plans, and bundled plans such as plan-US, planX3-EU, and plan-DU, include a fixed monthly cost. If you upgrade to a higher bundle, the higher bundle's fee applies for that month. If you downgrade, the higher bundle's fee still applies for that month, and the lower fee takes effect the following month.
• Activation charges: On Global coverage, a charge applies when a subscriber's status changes from Suspended or Standby to Active or Inactive.
• Subscription charges: Adding certain subscription containers (such as planP1, planX3, or plan-US-max) to a subscriber incurs a delivery charge and a monthly usage charge.
• Rounding: Data charges may be rounded up to the next minimum billing unit, shown as dataTrafficRoundedUpCharge in the detailed billing CSV.
• Options and services: Options such as Custom DNS, SMS, and application services such as Harvest Data are billed separately.

Reviewing Your Bill

To see exactly which charges make up your bill:

1. Log in to the User Console, click your account menu, then select Billing Dashboard.
2. Review the Costs by Service and Costs per SIM (Top 100) panels to see which services and SIMs account for the most charges.
3. On the Billing & Payment History tab, click Download service usage charges to download the Detailed Billing CSV. This file lists every charge by day and by IMSI, such as basicCharge and dataTrafficCharge records, along with discount records.

You can also retrieve per-SIM billing summaries for the last 4 months using the getBillingSummaryOfSims API (GET /bills/summaries/sims).

Contacting Support

After confirming the above, if the amount of data is still larger than expected, please enter the following information into a Support ticket:

• IMSI of the SIM that is utilizing the extra traffic
• Device that is being used (Raspberry Pi, WioLTE, etc.)
• Assumed communication volume and its breakdown (e.g., payload 128 bytes, UDP header 8 bytes, IP header 20 bytes, plus Soracom packet overhead of approximately 50-54 bytes)
• Date and time of communication