How to convert a file to a pbx-friendly format (8kHz, mono, PCM ulaw) with Audacity
In Audacity Edit – preferences – import/export – When exporting tracks to an audio file – use custom mix (done once) Open source file (mp3 or flac) Select Project Rate (bottom left) → 8000 File, export First time only: Select “Other uncompressed files” Click on “Options…” Choose Header → WAV (Microsoft), Encoding → U-Law On the Advanced Mixing Options, select 1 channel and add the unmapped channel to Channel 1 by clicking on the unmapped channel (it will get red borders) and then click on Channel: 1. Click OK Click OK at the “Edit Metadata” window Right-click on the output file, properties, summary, Advanced, make sure that: Channels = 1 (mono) Sample rate = 8kHz Format = CCITT u-Law