No indication or help on the compatibility

I find unacceptable the lack of information for such a price because no mention of this detail is made on the product page. I had to search several forums just to realize that my phone is not compatible, and yet, I still do not know what to look for.

I still managed to make it work using a RJ11 to RJ11 cable, which was not provided. But I doubt this is the intended use.