How to record in GSM instead of WAV to save disk

Recording every call in WAV is clean but heavy. WAV is uncompressed, so a busy floor fills a drive quickly. If disk space is the problem you are trying to solve, recording in GSM instead cuts the size of every file. This is how to make the switch.

Why GSM saves space

GSM is a compressed Codec built for voice. It throws away detail your ear barely notices on a phone call, and in return each recording is a fraction of the size of the same call in WAV. Over thousands of calls that difference is the gap between filling a drive in a month and filling it in a quarter. The Recording format (WAV/MP3) you choose is the single biggest lever on how much disk your recordings consume.

The cost is quality and convenience. GSM audio is fine for understanding a conversation but it is not pristine, and some playback or transcription tools expect WAV and need the file converted first. If your quality process or any outside system depends on WAV, test it before you switch everything over.

Be clear-eyed about what GSM trades for the savings. Speech recognition and automated transcription tend to do best with cleaner audio, so heavy compression can nudge accuracy down if you feed recordings into those tools. The same applies to any dispute where you need a customer's exact words proven beyond doubt. For most internal review the difference is negligible, but if a recording might ever serve as evidence, weigh that against the disk you save.

Making the switch

The format is controlled by the Campaign Rec extension on each campaign. The default is 8309, which records WAV. To record in GSM, change the Campaign Rec extension to 8310. That is the whole switch for Call recording format on that campaign. Both extensions still cap a recording at one hour by default, so this change only affects format and size, not length.

flowchart TD
  A[Open campaign settings] --> B[Find Campaign Rec extension]
  B --> C[Change 8309 to 8310]
  C --> D[Submit campaign]
  D --> E[Place a test call]
  E --> F{File is GSM}
  F -->|Yes| G[Disk usage drops]
  F -->|No| H[Recheck extension value]

1. Open the campaign you want to change.
2. Find the Campaign Rec extension field, currently 8309 for WAV.
3. Change it to 8310 to record in GSM and submit.
4. Place a test call and confirm the saved file is GSM before rolling it out widely.

Before you commit

Switch one campaign first and live with it for a few days. Check that your reviewers can play the files, that any transcription still runs, and that the quality is acceptable for your needs. Format is only one lever; combine GSM with a sensible retention policy and a recording delay that skips dead calls, and the three together do far more for your disk than any one alone.

Plan the rollout rather than flipping every campaign at once. Note the day you switch each one, since older WAV files and newer GSM files will sit side by side and you want to know which is which when you go looking later. If you ever need to reverse the change, set the extension back to 8309 and new recordings return to WAV; files already written keep whatever format they were recorded in. The deeper comparison of the two extensions is in our piece on the 8309 and 8310 recording extensions, and the overall strategy lives in our call recording guide.

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