AFAIK, this codec is perfect for voice, but bad for anything alese than voice.

I don't think ATA users will get anything out of a wideband codec. Although reading the signal power limitations of TIA-968-A gives me a headache, as best I can tell any phone meeting the requirements (which are the technical specs behind FCC Part 68 certification) basically are bandlimited at 4kHz.

I believe ATA users may get variable advantage from the use of wideband codecs. Some phones should be capable of passing some frequency components over 4Khz.

It is variable because it depends on the band filter sharpness off the phone as well. For example, a digital cordless phone might be more restrictive in this respect than a low tech plain analog phone plugged to the ATA.

This is unless ATA is using hard line filters for FXS ports as opposed to DSP based digital filtering. If DSP based filtering is used the software can fine tune.

I would like to see some stats using common equipment on the market before scrapping the idea for being stupid.