These SLICS would have depended on a codec's bandpass filter to filter out things outside of the voice band, as SLICS would have typically been connected to to a codec/filter and then to a TDM PCM highway for digital switching. If you are going to directly connect one of these to another SLIC, then external filtering would be required. As far muting the output during ringing, couldn't that be done by using a crosspoint switch matrix (e.g. MT8816) to connect the audio path to other SLICS and to the ESP32? The only thing which could be an issue is the spikes coupling through the crosspoint switch during ringing due to their fast rise times, but might be able to be solved with an RC snubber at the output of the bandpass filter.
These SLICS would have depended on a codec's bandpass filter to filter out things outside of the voice band, as SLICS would have typically been connected to to a codec/filter and then to a TDM PCM highway for digital switching. If you are going to directly connect one of these to another SLIC, then external filtering would be required. As far muting the output during ringing, couldn't that be done by using a crosspoint switch matrix (e.g. MT8816) to connect the audio path to other SLICS and to the ESP32? The only thing which could be an issue is the spikes coupling through the crosspoint switch during ringing due to their fast rise times, but might be able to be solved with an RC snubber at the output of the bandpass filter.