Free Audio Converter for Phone Systems
Your phone system rejects the file? Drop it here and convert MP3 to WAV, μ-law, a-law or 8 kHz mono in seconds.
- Free, no account needed
- WAV, MP3, FLAC, OGG, M4A in
- μ-law, a-law, G.711, G.722, MP3 out
Which setting to pick
Pick your device in the converter, or choose “Select format manually” and use the setting below.
| Phone system | Converter setting |
|---|---|
| Cloud phone systems (RingCentral, Zoom, Workspace Voice) | MP3 128kbps |
| Microsoft Teams Phone (auto attendants & queues) | WAV PCM 16kHz 16-bit |
| Traditional PBX (Asterisk, Cisco, Avaya) | WAV µ-law |
| Nextiva NextOS | WAV µ-law |
The converter is free. If the format you picked does not work on your phone system, simply convert the file again into another one, as often as you like. The audio format guide explains sample rate, mono and length limits.
Popular conversions for phone systems
Every setting below is in the converter above. Upload your file once and try another setting if your system wants something else.
MP3 to WAV
Most PBX upload pages ask for WAV. Pick “WAV PCM 8kHz 16-bit” when the system asks for 8 kHz, 16-bit, mono PCM, or “WAV µ-law” for 8-bit μ-law.
MP3 or WAV to μ-law and a-law
Choose “WAV µ-law” for 8 kHz, 8-bit, mono μ-law, common in North America. For a-law, common in Europe, choose “WAV a-law”.
Stereo 44.1 kHz to 8 kHz mono
Music and recordings usually come as 44.1 or 48 kHz stereo. Every WAV setting in the converter creates mono at 8 or 16 kHz.
iPhone voice memo (M4A) to WAV
Recorded your greeting on the phone? Upload the M4A file and download it as WAV for your phone system, or as MP3 for cloud systems.
Music on hold
Convert hold music and on-hold messages the same way. Optional settings adjust the volume and cut the file to a maximum length.
Asterisk and FreePBX sound files
Besides WAV μ-law, the converter creates raw SLN (8 kHz) and SLN16 (16 kHz), GSM and G.722 for Asterisk-based systems.
One-click presets
Your system is not listed? Choose “Select format manually” and pick the setting from the table above.
Upload rejected? What the message means
The wording differs from system to system. These are typical messages and the setting that usually solves them.
| Message on your phone system | What it usually means | Pick in the converter |
|---|---|---|
| “Unsupported file format” or “Invalid file type” | The system does not take MP3 or M4A. | WAV PCM 8kHz 16-bit or WAV µ-law |
| “WAV (PCM, 8 kHz, 16 bit, mono)” | The upload page names the exact format. | WAV PCM 8kHz 16-bit |
| “8 kHz, 8-bit, mono, CCITT μ-law” | The system stores greetings as telephone μ-law. | WAV µ-law |
| “Invalid sample rate” | The file has 44.1 or 48 kHz. | WAV PCM 8kHz 16-bit, or 16kHz if the system asks for it |
| “Audio must be mono” | The file is stereo. | Any WAV setting (all create mono) |
| “File too large” | The file is long or has a high bit rate. | WAV µ-law (about 0.5 MB per minute) or a maximum length in the optional settings |
How it works
Upload your file
Drag a WAV, MP3, FLAC, OGG or M4A file into the converter, or click to select it.
Pick your phone system
Choose a device preset, or select the format manually. Volume and maximum length are optional.
Download and upload
Download the converted file and upload it to your phone system. Our setup guide shows where.
Questions
Is the audio converter really free?
Yes. Upload a file, pick a format and download the result. No account and no subscription needed, and you do not have to be a phonegreetings.ai customer.
Which files can I upload?
WAV, MP3, FLAC, OGG and M4A, for example an iPhone voice memo or a music file for your hold queue.
Which formats can it create?
WAV μ-law and a-law (8 kHz, 8-bit, mono), WAV PCM at 8 or 16 kHz (8 or 16-bit, mono), MP3 at 128 or 256 kbps, G.711, G.722, G.726, GSM, Opus and raw SLN / SLN16 for Asterisk. You can also download all formats at once as a ZIP file.
What is μ-law, and do I need it?
μ-law (G.711 μ-law) is the classic 8 kHz telephone codec used in North America and Japan; a-law is its counterpart in Europe. Many traditional PBX and voicemail systems store greetings this way, while cloud systems usually take MP3 or standard WAV. If your upload page names a format, pick exactly that. If the file is rejected, convert it again into another format.
8 kHz or 16 kHz?
8 kHz is classic telephone quality and what most PBX systems ask for. 16 kHz (wideband or HD voice) sounds clearer on systems that support it, for example Microsoft Teams auto attendants or G.722 phones. A higher sample rate does not add quality the original file does not have.
Can I convert music on hold?
Yes. Upload the music file like any other recording. The optional settings let you adjust the volume and set a maximum length, which helps when your system limits the file size.
Do I need to install anything?
No. The converter runs in your web browser: upload, pick a setting, download.
My phone system is not in the device list. What do I choose?
Choose “Select format manually” and pick a setting from the table above. If the file does not play on your phone system, simply convert it again into another format. The converter is free, as often as you like.
Will converting make a poor recording sound better?
No. Converting changes the file format, not the recording. Background noise or a quiet voice stay in the file. If your greeting needs to sound professional, create a new one and preview it for free.
Phone system guides
- Audio format guideMP3 vs WAV, sample rate, mono vs stereo, length limits.
- How to set up a voicemail greetingWhere the file goes on your phone system.
- RingCentralIVR and voicemail audio upload.
- Microsoft TeamsTeams Phone voicemail and auto attendant.
- NextivaNextOS greeting upload and μ-law WAV.
- On-hold messagesCreate on-hold messages, then convert them here.
- All phone systemsSetup guides for every major platform.