You seem to be mainly interested in how Gigaset works with Phonak but I’ve used a Panasonic cordless handset with an iPhone since March and it works pretty well. The Link2Cell connection is standard classic Bluetooth and the set is supposed to work well either with an iPhone or an Android phone. With the iPhone, a text message or call to my iPhone dings or rings on any one of the five cordless handsets scattered about the house and the name of the texter or caller is announced if they are in my phone contacts. Either by turning on Do Not Disturb or turning off Bluetooth on my phone, I can keep the handset in the bedroom from dinging or ringing when either I or my wife is asleep (haven’t looked into whether I can set Do Not Disturb for individual handsets). I’m offering this post as a general contribution to the topic of your OP “Landline Phone Bluetooth Connectivity” for the benefit of anyone interested in that topic in general. Cordless phones for the hearing-challenged - #11 by jim_lewis. I can use a cordless phone pretty well without the sound streamed to my HA’s and even hear well enough to answer most calls when not wearing my hearing aids so my needs are less demanding than many other HA users(my linked post mentions that the handsets are T-coil-compatible but my HA’s don’t have a T-coil). We did away with our landline and the main thing the cordless handset does is give me phone receivers scattered throughout the house that run off my cell phone connected to the handset base station. Thus, I don’t have to lug a cell phone around the house with me to take a phone call ~anywhere in the house.