Well, I went and looked. Pocket your money. It's just an Analog Devices SSM2166 ($3.00) cell phone microphone processor chip with $2 of added parts. This chip is not designed for the kind of benefit Telstar claims, but instead, just equalizes a mic output level to avoid overloading an A/D converter. I built up a processor using one, and you only sound louder if you're already pretty loud to begin with. It won't help you get heard better if you're weak. This is traditional for all compression-based processors. Good if you're an AM broadcaster and want to sound LOUD (as the Wikipedia article on audio compression says), but not useful if you're weak signal.

RF clipping is far more effective. It's been used in long distance phone calls for nearly 100 years and you never thought of them as being distorted, did you?

It can be done completely external: create an SSB signal, clip it, then demodulate back to audio. The whole thing goes between your mic and the radio's mic jack.

Past examples that were very good are the Drake SP-75, Ten-Tec 234, and Datong RFC. A Google search for any of them will get you the schematic and most can be built for less parts cost than this Telstar thing.

I am aware of only one that is presently available, by DF4ZS, but the audio samples on his website demonstrate that he's got his design wrong, as it's loaded with audio, not RF clipping. Maybe you can buy one of those, and fix the problem...it needs more dynamic range in the audio section.