Zero-byte sessions, which are sometimes labeled as "sessions without data" in your dashboard, can indicate signaling sessions in proper connection sequence. However, in large volumes, these zero byte sessions generally indicate possible device configuration issues preventing successful data traffic. You can find zero-byte sessions in your dashboard under a single device's page, a SIM's details page, or our data usage reports.
Debugging steps and possible causes
Zero-byte sessions are generally caused by one of two issues:
1. The APN is incorrect
A device can attach to a network even if the APN is incorrect. However, the device cannot pass data with an incorrect APN. If the device's APN is incorrect, the device may display zero-byte sessions in your dashboard.
To debug this scenario, confirm that your device's APN is set to hologram.
2. Device firmware issue
A device with many zero-byte sessions in quick succession indicates excessive and unnecessary reconnects. This may be caused by improper connection logic by the device firmware or the cellular module's current configuration. For example, a device constantly trying to connect despite successfully opening data sessions will result in multiple zero-byte sessions over time.
To debug this scenario, audit the device's firmware to ensure that it is programmed to recognize and utilize successful connections. Also confirm that the device's timeout allows for ample time to receive a response message from the network when attempting to open a session.
It may also be helpful to refer to any device-level or network logs from the cellular module because these will provide the most accurate information about your device's behavior.
Find zero-byte sessions in a single device page
On your device's page, there is a Network Connections in the Last 48 Hours card. In this chart, blue represents data sessions during which data was transmitted. Pink represents closed network sessions without any data transmitted.
Find zero-byte sessions for a SIM
On a SIM's details page, open the Data usage tab. The report that displays will show zero-byte sessions broken down for the selected date range by:
- Recent sessions
- Total zero-byte sessions per profile
- Total zero-byte sessions per network
- Total zero-byte sessions per day
Identify zero-byte sessions across your fleet
All our data usage reports separate "productive sessions," or sessions in which data was successfully passed through a network, from zero-byte sessions. You can find zero-byte session information broken down across your fleet per day in the Overview tab, per SIM in the By SIM tab, and per device per day in the By SIM and day tab.