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  • USB Recording

Feature Overview

From firmware version and forward, any phone with USB Recording Feature can record a phone call to an attached USB drive in WAV file format. If the setting usb_storage_passphrase is set, the audio will be encrypted while recording. Audio is recorded using 16 bit format at 16kHz.

Playback of WAV files stored on a USB drive is possible provided there are no special characters in the filename. Any of the following special characters included in the filename will prevent the filename from being displayed: comma, /, \, #, ;, :, |, %, (, ), @, &, ?, ', ", *, >, <, and whitespaces.

Required Settings

On a USB Recording Feature supported phone, to be able to record or playback previously recorded files from an attached USB drive, usbrec_enable must be set to 'on' or 'true.' Once enabled, two feature keys can be assigned to any programmable key but also will be automatically added to the soft keys when in a call. The feature control keys are Record and Pause.

Recording Operation

With an active call, typical operation is:

  • Start Recording
  • Pause Recording
  • Resume Recording
  • Stop Recording

Below is a sample of the in-call keys with the USB Recording feature enabled, but not actively recording.

Actively recording will appear similar to the image below.

After pressing Pause, you have the option of Stop or Resume, as shown below.

Determining Available Recording Space

With a phone that has USB Recording Feature available and an attached USB drive, navigate to the USB Info page with the following steps:

  • Press Settings key
  • Scroll to Information, press OK
  • Scroll to USB Info, press OK

Depending on the size of the attached USB drive you will see a screen similar to the image below.

Listing Playback Files

With a phone that has USB Recording Feature available and usbrec_enable setting set to 'true' or 'on', navigate to Browser Recordings with the following steps:

  • Press Settings key
  • Scroll to Call Features, press OK
  • Scroll to Browse Recordings, press OK

A list of WAV files will be displayed similar to the image below

Playback Steps

Following the Listing Playback Files above, select the file you wish to play and press the Play soft key. See a sample image below.

The playback can be paused, deleted, or stopped.
When the file is not encrypted and actively playing Rewind and Fast Forward allow skipping forward or backward by 5 second intervals.
When encrypted and playing Rewind and Fast Forward do not appear, as skipping is not feasible with encrypted audio.


  • The recording is not supported for local (phone MCU) conference (2+1) calls. We suggest using remote conference call (server MCU) instead.
  • Rewind/Forward action is not available when playback encrypted recording
  • Filenames cannot contain whitespace