When an LTE IoT device is idle, it does not stay fully connected and instead enters in to Idle Mode to save resources and periodically checks for Paging messages from the network.
Here’s an example captured during field testing using QXDM:
Paging Messages seen on PCCH (Physical Control Channel)
Decoded TMSI shows target UE identity
Multiple Paging events detected → confirming network Paging cycle.
Validating Paging behaviour is an important part of field testing for IoT devices, helping ensure devices can correctly wake and respond to MT (Mobile Terminated) events such as:
• Incoming SMS
• Downlink data
• VoLTE call (if supported).
Next in the series, how eDRX further optimises idle behaviour for power saving 
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