If Soracom Air's data traffic volume is higher than expected, it is possible that the main reason is communication that was not taken into account, such as DNS queries, HTTP Keep-Alive, or packet overhead.
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
- Log in to the User Console.
- Select the SIM you wish to investigate and click Details.
- Click the Historical charts tab.
- Monthly cumulative total: Shows the cumulative total by day for the current month.
- Data usage: Shows historical data usage by month, day, or hour.
For more information, refer to the Checking 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 to retrieve data usage details.
Controlling and Restricting Data Usage
To prevent unexpected overages, you can use the Soracom Event Handler to set up notifications or bandwidth control.
For an example implementation, see our Disable SIMs That Use More Than 25MB in a Month confiugration.
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:
- Billable Data Usage: Including the packet overhead mentioned above.
- The SIM Plan: Whether it is Pay-As-You-Go or a bundled plan.
- 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.
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