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What is a "Purge" request in cellular signaling?

A "Purge" request is a network signal indicating that a device has become inactive.

Chandika Ambawatte avatar
Written by Chandika Ambawatte
Updated over 3 months ago

Environment

  • Cellular technology: applicable to all

  • Onomondo Core Network

  • Onomondo app: Signaling Logs

Question

  • What is a Purge Request in cellular signaling?

  • What is a Purge Request and why does it occur?

  • Why does a Purge Request sometimes happen right after the last data session ends?

Answer

A Purge Request is typically sent by the Radio Access Network (RAN) when a device becomes inactive for an extended period of time and stops communicating with the local network.

  • Typically, it occurs after 12-48 hours of inactivity.

  • If the "Purge" occurs immediately after the last data session - it can be an issue that requires further troubleshooting.

Cause

Purging subscriber information from the RAN's memory is part of normal cellular behavior and helps the RAN manage resources.

There is no reason to maintain subscriber information if the subscriber has left the network.

However, sometimes the RAN may send a "Purge" request unexpectedly. Unexpected or premature Purge Requests may be triggered by:

  • Device firmware misconfigurations, such as short inactivity timers or initiating attach procedures on CREG instead of CEREG or CGREG.

  • Device-specific handling errors, such as failing to resolve DNS, which prevents data sessions from initiating properly.

  • The network actively terminating the connection for the sake of resource management and load balancing.

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