Starting from firmware version 126.96.36.199, all Snom Desktop phones equipped with a USB port can store SIP traces on a mass-storage device. In this case the trace size is limited to the USB device free space only.
In order to enable this feature you need to:
Enable the usb_storage_siptrace: you can do it via provisioning or via phone web interface clicking on Advanced -> QoS/Security:
Create the "flag file" siptrace.flg into the root directory of the USB storage device:
Plug the USB device into the phone USB port, the phone should detect the storage device:
At this point the phone starts saving the sip trace on the USB device, once you reproduced the issue you can unmount and unplug the USB device. Un-mounting the device before unplugging is fundamental in order to avoid data corruptions.
The USB device can be un-mounted pressing the Menu key, selecting Maintenance and then Unmount USB disk: