Perhaps you wouldn’t like this Panasonic KX-TGF575S cordless handset system then but it’s working great for us. In the Amazon Q&A for the product a member of “Team Panasonic” says that the handsets are T-coil compatible but in speakerphone mode both the base and the handsets can be very loud, too. Paired with an iPhone, the base and each of the handsets can announce the name of the caller, if you’ve imported your phone contact list to the Panasonic base, or the calling number. The cordless handsets with an iPhone can also announce that you’ve gotten a text message and again, who it’s from. Used with an Android phone, the handset system can announce other Android notifications as well, too.
Basically the Link2Cell feature effectively greatly extends the range that you can be from your cell phone and still answer your cell phone anywhere in the house no matter if you’re in a distant room from where your cell phone is. I think (someone correct me if I’m wrong) that your cell phone has to be within classic BT distance of the base unit but since the base communicates with the cordless handset units using DETECT 6.0 technology, a lower, more penetrating RF frequency than 2.4 GHz BT, you can be up to 300 ft away from the base unit (and your cell phone) and still take and make phone calls through your cell phone using a handset. But with my cell phone in the bedroom, the base unit in the kitchen about 30 feet away, I can answer a call to my cell phone using the cordless handset, which is easier to answer than my iPhone, and the call clarity is pretty good. I tried an indoor/outdoor experiment with my wife and carrying a cordless handset clipped to my belt, I could go out into the yard about 150 feet away from the house and still answer a call to my cell phone left in the kitchen from her cell phone, loud and clear. When it’s 107 degrees or so outside in the summer, I don’t want to be carrying my cell phone outside the house for long periods since it’s battery isn’t easily replaceable if I kill it with the heat but the special NiMH batteries in a Panasonic cordless handset are easily replaceable (not cheap, though). My only regret is that the handsets are not rated highly for dust or water resistance so they need some TLC if taken outdoors or being used near dirty, dusty work.
When I got our Panasonic system back in March, a unit with 3 handsets was ~$120, a unit with 5 handsets was $133, so we got the one with 5 handsets and now have them distributed all around the house, replacing a much older 2008 Panasonic cordless system. It was worth it just for the caller-announcing feature and the call blocking feature (works at least as far as blocking handset ringing goes, haven’t analyzed whether it feeds back to cell phone ringing).